@article{kugler-umana_zhang_kuang_liang_castonguay_tonkonogy_marshak-rothstein_devarajan_swain_2022, title={IgD(+) age-associated B cells are the progenitors of the main T-independent B cell response to infection that generates protective Ab and can be induced by an inactivated vaccine in the aged}, ISSN={["1474-9726"]}, DOI={10.1111/acel.13705}, abstractNote={Abstract}, journal={AGING CELL}, author={Kugler-Umana, Olivia and Zhang, Wenliang and Kuang, Yi and Liang, Jialing and Castonguay, Catherine H. and Tonkonogy, Susan L. and Marshak-Rothstein, Ann and Devarajan, Priyadharshini and Swain, Susan L.}, year={2022}, month={Sep} }
 @article{surman_crawford_dash_tonkonogy_thomas_hurwitz_2022, title={Microbiome Shapes the T Cell Receptor Repertoire among CD4+CD8+ Thymocytes}, volume={10}, ISSN={["2227-9059"]}, DOI={10.3390/biomedicines10123015}, abstractNote={The microbiome shapes the mature T cell receptor (TCR) repertoire and thereby influences pathogen control. To investigate microbiome influences on T cells at an earlier, immature stage, we compared single-cell TCR transcript sequences between CD4+CD8+ (double-positive) thymocytes from gnotobiotic [E. coli mono-associated (Ec)] and germ-free (GF) mice. Identical TCRβ transcripts (termed repeat, REP) were more often shared between cells of individual Ec mice compared to GF mice (Fishers Exact test, p < 0.0001). Among Ec REPs, a cluster of Vβ genes (Vβ12-1, 12-2, 13-1, and 13-2, termed 12-13) was well represented, whereas 12-13 sequences were not detected among GF REPs (Fishers Exact test, p = 0.046). Vα genes located in the distal region of the TCRα locus were more frequently expressed in Ec mice compared to GF mice, both among REPs and total sequences (Fishers Exact test, p = 0.009). Results illustrate how gut bacteria shape the TCR repertoire, not simply among mature T cells, but among immature CD4+CD8+ thymocytes.}, number={12}, journal={BIOMEDICINES}, author={Surman, Sherri L. L. and Crawford, Jeremy and Dash, Pradyot and Tonkonogy, Susan L. L. and Thomas, Paul G. G. and Hurwitz, Julia L. L.}, year={2022}, month={Dec} }
 @article{schmitz_tonkonogy_dogan_leblond_whitehead_kim_simpson_sartor_2019, title={Murine Adherent and Invasive E. coli Induces Chronic Inflammation and Immune Responses in the Small and Large Intestines of Monoassociated IL-10(-/-) Mice Independent of Long Polar Fimbriae Adhesin}, volume={25}, ISSN={["1536-4844"]}, DOI={10.1093/ibd/izy386}, abstractNote={BACKGROUND
Adherent and invasive Escherichia coli (AIEC) is preferentially associated with ileal Crohn's disease (CD). The role of AIEC in the development of inflammation and its regional tropism is unresolved. The presence of long polar fimbriae (LPF) in 71% of ileal CD AIEC suggests a role for LPF in the tropism and virulence of AIEC. The aim of our study is to determine if AIEC, with or without LpfA, induces intestinal inflammation in monoassociated IL-10-/- mice.


METHODS
We compared murine AIEC strains NC101 (phylogroup B2, LpfA-) and CUMT8 (phylogroup B1, LpfA+), and isogenic mutant CUMT8 lacking lpfA154, with a non-AIEC (E. coli K12), evaluating histologic inflammation, bacterial colonization, mucosal adherence and invasion, and immune activation.


RESULTS
IL-10-/- mice monoassociated with AIEC (either CUMT8, CUMT8:ΔlpfA, or NC101) but not K12 developed diffuse small intestinal and colonic inflammation. There was no difference in the magnitude and distribution of inflammation in mice colonized with CUMT8:ΔlpfA compared with wild-type CUMT8. Bacterial colonization was similar for all E. coli strains. Fluorescence in situ hybridization revealed mucosal adherence and tissue invasion by AIEC but not K12. Production of the cytokines IL-12/23 p40 by the intestinal tissue and IFN-γ and IL-17 by CD4 T cells correlated with inflammation.


CONCLUSIONS
IL-10-/- mice monoassociated with murine AIEC irrespective of LpfA expression developed chronic inflammation accompanied by IL-12/23 p40 production in the small and large intestines and IFN-γ/IL-17 production by CD4 T cells that model the interplay between enteric pathosymbionts, host susceptibility, and enhanced immune responses in people with IBD.}, number={5}, journal={INFLAMMATORY BOWEL DISEASES}, author={Schmitz, Julia M. and Tonkonogy, Susan L. and Dogan, Belgin and Leblond, Anna and Whitehead, Kristi J. and Kim, Sandra C. and Simpson, Kenneth W. and Sartor, R. Balfour}, year={2019}, month={May}, pages={875–885} }
 @article{wu_sartor_huang_tonkonogy_2016, title={Transient activation of mucosal effector immune responses by resident intestinal bacteria in normal hosts is regulated by interleukin-10 signalling}, volume={148}, ISSN={["1365-2567"]}, DOI={10.1111/imm.12612}, abstractNote={Summary}, number={3}, journal={IMMUNOLOGY}, author={Wu, Cong and Sartor, R. Balfour and Huang, Kehe and Tonkonogy, Susan L.}, year={2016}, month={Jul}, pages={304–314} }
 @article{packey_shanahan_manick_bower_ellermann_tonkonogy_carroll_sartor_2013, title={Molecular detection of bacterial contamination in gnotobiotic rodent units}, volume={4}, ISSN={1949-0976 1949-0984}, url={http://dx.doi.org/10.4161/gmic.25824}, DOI={10.4161/gmic.25824}, abstractNote={Gnotobiotic rodents provide an important technique to study the functional roles of commensal bacteria in host physiology and pathophysiology. To ensure sterility, these animals must be screened frequently for contamination. The traditional screening approaches of culturing and Gram staining feces have inherent limitations, as many bacteria are uncultivable and fecal Gram stains are difficult to interpret. Thus, we developed and validated molecular methods to definitively detect and identify contamination in germ-free (GF) and selectively colonized animals. Fresh fecal pellets were collected from rodents housed in GF isolators, spontaneously contaminated ex-GF isolators, selectively colonized isolators and specific pathogen-free (SPF) conditions. DNA isolated from mouse and rat fecal samples was amplified by polymerase chain reaction (PCR) and subjected to quantitative PCR (qPCR) using universal primers that amplify the 16S rRNA gene from all bacterial groups. PCR products were sequenced to identify contaminating bacterial species. Random amplification of polymorphic DNA (RAPD) PCR profiles verified bacterial inoculation of selectively colonized animals. These PCR techniques more accurately detected and identified GF isolator contamination than current standard approaches. These molecular techniques can be utilized to more definitively screen GF and selectively colonized animals for bacterial contamination when Gram stain and/or culture results are un-interpretable or inconsistent.}, number={5}, journal={Gut Microbes}, publisher={Informa UK Limited}, author={Packey, Christopher D and Shanahan, Michael T and Manick, Sayeed and Bower, Maureen A and Ellermann, Melissa and Tonkonogy, Susan L and Carroll, Ian M and Sartor, R Balfour}, year={2013}, month={Sep}, pages={361–370} }
 @article{liu_tonkonogy_sartor_2011, title={Antigen-Presenting Cell Production of IL-10 Inhibits T-Helper 1 and 17 Cell Responses and Suppresses Colitis in Mice}, volume={141}, ISSN={["0016-5085"]}, DOI={10.1053/j.gastro.2011.04.053}, abstractNote={BACKGROUND & AIMS
Mice that are deficient in interleukin (IL)-10 develop colitis, mediated by T-helper (Th)1 and Th17 cells, and IL-10-producing regulatory T (Treg) cells suppress colitis, implicating IL-10 in maintaining mucosal homeostasis. We assessed the relative importance of immunoregulatory IL-10 derived from T cells or from antigen presenting cells (APCs) in development of intestinal inflammation.


METHODS
CD4(+) cells from germ-free (GF) or specific pathogen-free (SPF) IL-10(-/-) or wild-type mice were injected into IL-10(-/-), Rag2(-/-) mice or Rag2(-/-) mice that express IL-10. After 6-8 weeks, we evaluated inflammation, spontaneous secretion of cytokines from colonic tissue, and mRNA levels of the transcription factor T-bet and the immunoregulatory cytokine transforming growth factor (TGF)-β. CD4(+) T cells were co-cultured with bacterial lysate-pulsed APCs and assayed for cytokine production, FoxP3 expression, and TGF-β-mediated Smad signaling.


RESULTS
CD4(+) cells from GF or SPF IL-10(-/-) or wild-type mice induced more severe colitis and higher levels of inflammatory cytokines in IL-10(-/-), Rag2(-/-) mice than in IL-10-replete, Rag2(-/-) mice. Co-cultures of IL-10(-/-) or wild-type CD4(+) T cells plus bacterial lysate-pulsed APCs from IL-10(-/-) mice contained more interferon (IFN)-γ, IL-12/23p40, and IL-17 than co-cultures of the same T cells plus APCs from wild-type mice. CD11b(+) APCs were required for these effects. Blocking IL-10 receptors increased production of IFN-γ and IL-12/23p40 whereas exogenous IL-10 suppressed these cytokines. IL-10-producing APCs induced TGF-β-mediated, retinoic acid-dependent, differentiation of FoxP3(+) Treg cells, whereas blocking the retinoic acid receptor, in vitro and in vivo, reduced proportions of FoxP3(+) Treg cells.


CONCLUSIONS
IL-10 produced by APCs regulates homeostatic T-cell responses to commensal bacteria.}, number={2}, journal={GASTROENTEROLOGY}, author={Liu, Bo and Tonkonogy, Susan L. and Sartor, R. Balfour}, year={2011}, month={Aug}, pages={653–U764} }
 @article{steck_hoffmann_sava_kim_hahne_tonkonogy_mair_krueger_pruteanu_shanahan_et al._2011, title={Enterococcus faecalis Metalloprotease Compromises Epithelial Barrier and Contributes to Intestinal Inflammation}, volume={141}, ISSN={["0016-5085"]}, DOI={10.1053/j.gastro.2011.05.035}, abstractNote={BACKGROUND & AIMS
Matrix metalloproteases (MMPs) mediate pathogenesis of chronic intestinal inflammation. We characterized the role of the gelatinase (GelE), a metalloprotease from Enterococcus faecalis, in the development of colitis in mice.


METHODS
Germ-free, interleukin-10-deficient (IL-10(-/-)) mice were monoassociated with the colitogenic E faecalis strain OG1RF and isogenic, GelE-mutant strains. Barrier function was determined by measuring E-cadherin expression, transepithelial electrical resistance (TER), and translocation of permeability markers in colonic epithelial cells and colon segments from IL-10(-/-) and TNF(ΔARE/Wt) mice. GelE specificity was shown with the MMP inhibitor marimastat.


RESULTS
Histologic analysis (score 0-4) of E faecalis monoassociated IL-10(-/-) mice revealed a significant reduction in colonic tissue inflammation in the absence of bacteria-derived GelE. We identified cleavage sites for GelE in the sequence of recombinant mouse E-cadherin, indicating that it might be degraded by GelE. Experiments with Ussing chambers and purified GelE revealed the loss of barrier function and extracellular E-cadherin in mice susceptible to intestinal inflammation (IL-10(-/-) and TNF(ΔARE/Wt) mice) before inflammation developed. Colonic epithelial cells had reduced TER and increased translocation of permeability markers after stimulation with GelE from OG1RF or strains of E faecalis isolated from patients with Crohn's disease and ulcerative colitis.


CONCLUSIONS
The metalloprotease GelE, produced by commensal strains of E faecalis, contributes to development of chronic intestinal inflammation in mice that are susceptible to intestinal inflammation (IL-10(-/-) and TNF(ΔARE/Wt) mice) by impairing epithelial barrier integrity.}, number={3}, journal={GASTROENTEROLOGY}, author={Steck, Natalie and Hoffmann, Micha and Sava, Irina G. and Kim, Sandra C. and Hahne, Hannes and Tonkonogy, Susan L. and Mair, Katrin and Krueger, Dagmar and Pruteanu, Mihaela and Shanahan, Fergus and et al.}, year={2011}, month={Sep}, pages={959–971} }
 @article{lee_wyse_lesher_everett_lou_holzknecht_whitesides_spears_bowles_lin_et al._2010, title={Adaptation in a Mouse Colony Monoassociated with Escherichia coli K-12 for More than 1,000 Days}, volume={76}, ISSN={["0099-2240"]}, DOI={10.1128/aem.00358-10}, abstractNote={ABSTRACT}, number={14}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Lee, Sean M. and Wyse, Aaron and Lesher, Aaron and Everett, Mary Lou and Lou, Linda and Holzknecht, Zoie E. and Whitesides, John F. and Spears, Patricia A. and Bowles, Dawn E. and Lin, Shu S. and et al.}, year={2010}, month={Jul}, pages={4655–4663} }
 @inproceedings{moran_walter_tannock_tonkonogy_sartor_2009, title={Bifidobacterium animalis causes extensive duodenitis and mild colonic inflammation in monoassociated interleukin-lO-deficient mice}, volume={15}, DOI={10.1002/ibd.20900}, abstractNote={Background: We recently showed that Bifidobacterium animalis is more prevalent within the colons of interleukin (IL)‐10‐deficient (−/−) mice than in wildtype (WT) animals colonized with the same specific pathogen‐free (SPF) fecal contents. Here we tested the ability of this organism to cause T‐cell‐mediated intestinal inflammation by introducing it into germ‐free (GF) IL‐10−/− mice. Methods: GF IL‐10−/− or WT mice were monoassociated with Bifidobacterium animalis subsp. animalis ATCC (American Type Culture Collection, Manassas, VA) 25527T or with B. infantis ATCC 15697T. Inflammation was measured by blinded histologic scores of the duodenum, cecum, and colon and by spontaneous secretion of IL‐12/IL‐23 p40 from colonic explants. Bacterial antigen‐specific CD4+ mesenteric lymph node (MLN) T‐cell recall responses were measured in response to antigen‐presenting cells (APC) pulsed with bacterial lysates. Results: B. animalis caused marked duodenal inflammation and mild colitis in monoassociated IL‐10−/− mice, whereas the intestinal tracts of WT animals remained free of inflammation. B. infantis colonization resulted in mild inflammation in the duodena of IL‐10−/− mice. CD4+ MLN T cells from B. animalis monoassociated IL‐10−/− mice secreted high levels of IFN‐&ggr; and IL‐17 in response to B. animalis lysate. B. animalis equally colonized the different intestinal regions of WT and IL‐10−/− mice. Conclusions: B. animalis, a traditional probiotic species that is expanded in experimental colitis in this model, induces marked duodenal and mild colonic inflammation and TH1/TH17 immune responses when introduced alone into GF IL‐10−/− mice. This suggests a potential pathogenic role for this commensal bacterial species in a susceptible host.}, number={7}, booktitle={Inflammatory Bowel Diseases}, author={Moran, J. P. and Walter, J. and Tannock, G. W. and Tonkonogy, S. L. and Sartor, R. B.}, year={2009}, pages={1022–1031} }
 @article{albright_sartor_tonkonogy_2009, title={Endogenous antigen presenting cell-derived IL-10 inhibits T lymphocyte responses to commensal enteric bacteria}, volume={123}, ISSN={["1879-0542"]}, DOI={10.1016/j.imlet.2009.02.010}, abstractNote={Interleukin-10 deficient (IL-10-/-) mice develop chronic T cell-mediated colitis when colonized with normal commensal bacteria, but germ-free (GF) IL-10-/- mice remain disease-free. Antigen presenting cells (APC) secrete regulatory cytokines that help determine T lymphocyte activation or tolerance. CD4(+) T cells from the mesenteric lymph nodes of inflamed IL-10-/- mice secrete more IFN-gamma and IL-17 when cultured with cecal bacterial lysate-pulsed splenic APC from IL-10-/- mice than when cultured with normal control APC. GF IL-10-/- APC induce similar IFN-gamma and IL-17 responses; therefore, the functional difference between normal and IL-10 deficient APC is inherent to the lack of IL-10 and not secondary to inflammation. Bacterial lysate-pulsed normal APC cultured with CD4(+) cells from colitic IL-10-/- mice or with exogenous IFN-gamma secrete higher amounts of IL-10 compared to the same APC cultured with naïve T cells. APC enriched for CD11c(+) cells are potent activators of IFN-gamma and IL-17 production by CD4(+) cells from IL-10-/- mice. These APC also produce IL-12/IL-23 p40 and IL-10. Recombinant IL-10 suppressed and anti-IL-10 receptor antibody increased IFN-gamma, IL-17 and IL-12/IL-23 p40 production in bacterial lysate-pulsed APC and plus CD4(+) T cell co-cultures. Taken together, our results show that endogenous IL-10 produced by APC inhibits responses to commensal bacteria and influences the ability of APC to stimulate IFN-gamma-producing effector lymphocytes, which reciprocally, induce IL-10 production by APC. Cytokines produced by APC are an important determinant of pathogenic versus protective mucosal immune responses to colonic bacterial stimulation.}, number={1}, journal={IMMUNOLOGY LETTERS}, author={Albright, Carol A. and Sartor, R. Balfour and Tonkonogy, Susan L.}, year={2009}, month={Mar}, pages={77–87} }
 @article{qian_tonkonogy_sartor_2008, title={Aberrant Innate Immune Responses in TLR-ligand Activated HLA-B27 Transgenic Rat Cells}, volume={14}, ISSN={["1536-4844"]}, DOI={10.1002/ibd.20502}, abstractNote={Background: Commensal enteric microbiota initiate and perpetuate immune‐mediated colitis in HLA‐B27 transgenic (TG) rats but not wildtype (non‐TG) littermates. However, the role of the innate immune response to bacterial components has not been established. Methods: We examined responses induced by bacterial adjuvants through Toll‐like receptor (TLR) and NOD2 signaling in T‐cell‐depleted splenocytes from HLA‐B27 TG rats versus non‐TG controls. Results: We found that various bacterial adjuvants induced TNF production by cells obtained from specific pathogen‐free (SPF) and germ‐free (GF, sterile) TG and non‐TG rats. Peptidoglycan‐polysaccharide (PG‐PS), lipopolysaccharide (LPS), and CpG DNA motifs stimulated higher levels of TNF production by SPF TG rat spleen cells compared to non‐TG cells. CD11b/c cell depletion eliminated PG‐PS and LPS‐induced TNF and dramatically reduced CpG‐stimulated TNF production. Both SPF and GF TG rat spleens contain more cells that express high levels of CD11b/c and show enhanced mRNA expression of TLR‐2 and TLR‐4 compared to non‐TG rat spleens. In contrast, constitutive and bacterial‐induced IL‐10 production was markedly lower in TG cells compared to non‐TG cells of rats from the same SPF or GF housing conditions. Notably, the ratio of TNF to IL‐10 produced after TLR ligand activation was significantly higher in TG than non‐TG cells. Conclusions: HLA‐B27 TG rats have an aberrant cell composition, altered functional TLR expression, and an intrinsic defect in IL‐10 production in response to TLR ligands, which may result in exaggerated proinflammatory responses to commensal enteric bacteria and uncontrolled inflammation in this colitis model.}, number={10}, journal={INFLAMMATORY BOWEL DISEASES}, author={Qian, Bi-Feng and Tonkonogy, Susan L. and Sartor, R. Balfour}, year={2008}, month={Oct}, pages={1358–1365} }
 @article{qian_tonkonogy_sartor_2008, title={Reduced responsiveness of HLA-B27 transgenic rat cells to TGF-beta and IL-10-mediated regulation of IFN-gamma production}, volume={14}, ISSN={["1536-4844"]}, DOI={10.1002/ibd.20415}, abstractNote={Background: We have reported that commensal luminal bacterial components induce an active in vitro IFN‐&ggr; response in mesenteric lymph node (MLN) and intestinal cells from specific pathogen‐free (SPF) HLA‐B27 transgenic (TG) rats with chronic colitis but not in cells from non‐diseased SPF non‐TG, germ‐free (GF) non‐TG or GF TG rats. Methods: The study examined IL‐12 stimulation of MLN IFN‐&ggr; responses to luminal bacteria and regulation of these responses by suppressive cytokines. Results: Exogenous IL‐12 significantly increased the bacterial lysate‐induced IFN‐&ggr; response in SPF TG MLN cells, while bacterial lysate and IL‐12 synergistically induced IFN‐&ggr; from low baseline levels in cells obtained from both SPF and GF non‐TG rats, and in GF TG cells. TGF‐&bgr; fully counteracted the effects of IL‐12 and bacterial lysate on non‐TG cells by almost completely inhibiting IFN‐&ggr; production. In contrast, TG cells were less responsive to TGF‐&bgr;‐mediated downregulation with a substantial residual IFN‐&ggr; response to IL‐12 plus bacterial lysate. Further experiments showed that CD4+/CD25+ cells had no inhibitory effect on the IFN‐&ggr; production and were not required for TGF‐&bgr;‐mediated suppression. Addition of exogenous IL‐10 also partially inhibited IFN‐&ggr; production by non‐TG cells but did not affect TG cells. Conversely, exogenous IL‐12 preferentially suppressed bacterial lysate‐induced TGF‐&bgr; and IL‐10 production in TG rat cells. Conclusions: An attenuated response to regulatory signals leads to uncontrolled potentiated induction of effector IFN‐&ggr; responses to commensal bacteria in HLA‐B27 TG rats that spontaneously develop chronic intestinal inflammation.}, number={7}, journal={INFLAMMATORY BOWEL DISEASES}, author={Qian, Bi-Feng and Tonkonogy, Susan L. and Sartor, R. Balfour}, year={2008}, month={Jul}, pages={921–930} }
 @article{meng_newburg_young_baker_tonkonogy_sartor_walker_nanthakumar_2007, title={Bacterial symbionts induce a FUT2-dependent fucosylated niche on colonic epithelium via ERK and JNK signaling}, volume={293}, ISSN={0193-1857 1522-1547}, url={http://dx.doi.org/10.1152/ajpgi.00010.2007}, DOI={10.1152/ajpgi.00010.2007}, abstractNote={ The intestinal epithelium of the adult gut supports a complex, dynamic microbial ecosystem and expresses highly fucosylated glycans on its surface. Uncolonized gut contains little fucosylated glycan. The transition toward adult colonization, such as during recovery from germ-free status or from antibiotic treatment, increased expression of fucosylated epitopes in the colonic epithelium. This increase in fucosylation is accompanied by induction of fut2 mRNA expression and α1,2/3-fucosyltransferase activity. Colonization stimulates ERK and JNK signal transduction pathways, resulting in activation of transcription factors ATF2 and c-Jun, respectively. This increases transcription of fut2 mRNA and expression of α1,2/3-fucosyltransferase activity, resulting in a highly fucosylated intestinal mucosa characteristic of the adult mammalian gut. Blocking the ERK and JNK signaling cascade inhibits the ability of colonization to induce elevated fut2 mRNA and fucosyltransferase activity in the mature colon. Thus pioneer-mutualist symbiotic bacteria may utilize the ERK and JNK signaling cascade to induce the high degree of fucosylation characteristic of adult mammalian colon, and we speculate that this fucosylation facilitates colonization by adult microbiota. }, number={4}, journal={American Journal of Physiology-Gastrointestinal and Liver Physiology}, publisher={American Physiological Society}, author={Meng, Di and Newburg, David S. and Young, Cheryl and Baker, Amy and Tonkonogy, Susan L. and Sartor, R. Balfour and Walker, W. Allan and Nanthakumar, N. Nanda}, year={2007}, month={Oct}, pages={G780–G787} }
 @article{hoentjen_tonkonogy_qian_liu_dieleman_sartor_2007, title={CD4(+) T lymphocytes mediate colitis in HLA-B27 transgenic rats monoassociated with nonpathogenic Bacteroides vulgatus}, volume={13}, ISSN={["1078-0998"]}, DOI={10.1002/ibd.20040}, abstractNote={Background HLA‐B27/&bgr;2 microglobulin transgenic (TG) rats develop spontaneous colitis when raised under specific pathogen‐free (SPF) conditions or after monoassociation with Bacteroides vulgatus (B. vulgatus), whereas germ‐free TG rats fail to develop intestinal inflammation. SPF HLA‐B27 TG rnu/rnu rats, which are congenitally athymic, remain disease free. These results indicate that commensal intestinal bacteria and T cells are both pivotal for the development of colitis in TG rats. However, it is not known if T cells are also required in the induction of colitis by a single bacterial strain. The aim of this study was therefore to investigate the role of T cells in the development of colitis in B. vulgatus–monoassociated HLA‐B27 TG rats. Methods HLA‐B27 TG rnu/rnu and rnu/+ rats were monoassociated with B. vulgatus for 8–12 weeks. CD4+ T cells from mesenteric lymph nodes (MLNs) of B. vulgatus–monoassociated rnu/+ TG donor rats were transferred into B. vulgatus–monoassociated rnu/rnu TG recipients. Results B. vulgatus–monoassociated rnu/+ rats showed higher histologic inflammatory scores and elevated colonic interferon‐&ggr; mRNA, cecal myeloperoxidase, and cecal IL‐1&bgr; levels compared to those in rnu/rnu TG rats that did not contain T cells. After transfer of CD4+ cells from colitic B. vulgatus–monoassociated rnu/+ TG donor rats, B. vulgatus–monoassociated rnu/rnu TG recipients developed colitis that was accompanied by B. vulgatus‐induced IFN‐&ggr; production by MLN cells in vitro and inflammatory parameters similar to rnu/+ TG rats. Conclusions These results implicate CD4+ T cells in the development of colitis in HLA‐B27 TG rats monoassociated with the nonpathogenic bacterial strain B. vulgatus. (Inflamm Bowel Dis 2007)}, number={3}, journal={INFLAMMATORY BOWEL DISEASES}, author={Hoentjen, Frank and Tonkonogy, Susan L. and Qian, Bi-Feng and Liu, Bo and Dieleman, Levinus A. and Sartor, R. Balfour}, year={2007}, month={Mar}, pages={317–324} }
 @article{kim_tonkonogy_karrasch_jobin_sartor_2007, title={Dual-association of gnotobiotic IL-10-/- mice vith 2 nonpathogenic commensal bacteria induces aggressive pancolitis}, volume={13}, ISSN={["1078-0998"]}, DOI={10.1002/ibd.20246}, abstractNote={Background: Monoassociating gnotobiotic IL‐10‐deficient (−/−) mice with either nonpathogenic Enterococcus faecalis or a nonpathogenic Escherichia coli strain induces T‐cell‐mediated colitis with different kinetics and anatomical location (E. faecalis: late onset, distal colonic; E. coli: early onset, cecal). Hypothesis: E. faecalis and E. coli act in an additive manner to induce more aggressive colitis than disease induced by each bacterial species independently. Methods: Germ‐free (GF) inbred 129S6/SvEv IL‐10−/− and wildtype (WT) mice inoculated with nonpathogenic E. faecalis and/or E. coli were killed 3–7 weeks later. Colonic segments were scored histologically for inflammation (0 to 4) or incubated in media overnight to measure spontaneous IL‐12/IL‐23p40 secretion. Bacterial species were quantified by serial dilution and plated on culture media. Mesenteric lymph node (MLN) CD4+ cells were stimulated with antigen‐presenting cells pulsed with bacterial lysate (E. faecalis, E. coli, Bacteroides vulgatus) or KLH (unrelated antigen control). IFN‐&ggr; and IL‐17 levels were measured in the supernatants. Results: Dual‐associated IL‐10−/− (but not WT) mice developed mild‐to‐moderate pancolitis by 3 weeks that progressed to severe distal colonic‐predominant pancolitis with reactive atypia and duodenal inflammation by 7 weeks. NF‐&kgr;B was activated in the duodenum and colon in dual‐associated IL‐10−/− × NF‐&kgr;BEGFP mice. The aggressiveness of intestinal inflammation and the degree of antigen‐specific CD4+ cell activation were greater in dual‐ versus monoassociated IL‐10−/− mice. Conclusion: Two commensal bacteria that individually induce phenotypically distinct colitis in gnotobiotic IL‐10−/− mice act additively to induce aggressive pancolitis and duodenal inflammation. (Inflamm Bowel Dis 2007)}, number={12}, journal={INFLAMMATORY BOWEL DISEASES}, author={Kim, Sandra C. and Tonkonogy, Susan L. and Karrasch, Thomas and Jobin, Christian and Sartor, R. Balfour}, year={2007}, month={Dec}, pages={1457–1466} }
 @article{hoentjen_tonkonogy_liu_sartor_taurog_dieleman_2006, title={Adoptive transfer of nontransgenic mesenteric lymph node cells induces colitis in athymic HLA-B27 transgenic nude rats}, volume={143}, ISSN={["1365-2249"]}, DOI={10.1111/j.1365-2249.2006.03013.x}, abstractNote={Summary}, number={3}, journal={CLINICAL AND EXPERIMENTAL IMMUNOLOGY}, author={Hoentjen, F and Tonkonogy, SL and Liu, B and Sartor, RB and Taurog, JD and Dieleman, LA}, year={2006}, month={Mar}, pages={474–483} }
 @article{qian_tonkonogy_sartor_2006, title={Luminal bacterial antigen-specific CD4(+) T-cell responses in HLA-B27 transgenic rats with chronic colitis are mediated by both major histocompatibility class II and HLA-B27 molecules}, volume={117}, ISSN={["1365-2567"]}, DOI={10.1111/j.1365-2567.2005.02303.x}, abstractNote={Summary}, number={3}, journal={IMMUNOLOGY}, author={Qian, BF and Tonkonogy, SL and Sartor, RB}, year={2006}, month={Mar}, pages={319–328} }
 @article{qian_tonkonogy_hoentjen_dieleman_sartor_2005, title={Dysregulated luminal bacterial antigen-specific T-cell responses and antigen-presenting cell function in HLA-B27 transgenic rats with chronic colitis}, volume={116}, ISSN={["1365-2567"]}, DOI={10.1111/j.1365-2567.2005.02206.x}, abstractNote={Summary}, number={1}, journal={IMMUNOLOGY}, author={Qian, BF and Tonkonogy, SL and Hoentjen, F and Dieleman, LA and Sartor, RB}, year={2005}, month={Sep}, pages={112–121} }
 @article{kim_tonkonogy_albright_tsang_balish_braun_huycke_sartor_2005, title={Variable phenotypes of enterocolitis in interleukin 10-deficient mice monoassociated with two different commensal bacteria}, volume={128}, ISSN={["1528-0012"]}, DOI={10.1053/j.gastro.2005.02.009}, abstractNote={BACKGROUND & AIMS
To explore the hypothesis that selective immune responses to distinct components of the intestinal microflora induce intestinal inflammation, we characterized disease kinetics and bacterial antigen-specific T-cell responses in ex germ-free interleukin 10 -/- and wild-type control mice monoassociated with Enterococcus faecalis , Escherichia coli , or Pseudomonas fluorescens .


METHODS
Colitis was measured by using blinded histological scores and spontaneous interleukin 12 secretion from colonic strip culture supernatants. Interferon gamma secretion was measured from mesenteric or caudal lymph node CD4 + T cells stimulated with bacterial lysate-pulsed antigen-presenting cells. Luminal bacterial concentrations were measured by culture and quantitative polymerase chain reaction.


RESULTS
Escherichia coli induced mild cecal inflammation after 3 weeks of monoassociation in interleukin 10 -/- mice. In contrast, Enterococcus faecalis-monoassociated interleukin 10 -/- mice developed distal colitis at 10-12 weeks that was progressively more severe and associated with duodenal inflammation and obstruction by 30 weeks. Neither bacterial strain induced inflammation in wild-type mice, and germ-free and Pseudomonas fluorescens-monoassociated interleukin 10 -/- mice remained disease free. CD4 + T cells from Enterococcus faecalis- or Escherichia coli-monoassociated interleukin 10 -/- mice selectively produced higher levels of interferon gamma and interleukin 4 when stimulated with antigen-presenting cells pulsed with the bacterial species that induced disease; these immune responses preceded the onset of histological inflammation in Enterococcus faecalis -monoassociated mice. Luminal bacterial concentrations did not explain regional differences in inflammation.


CONCLUSIONS
Different commensal bacterial species selectively initiate immune-mediated intestinal inflammation with distinctly different kinetics and anatomic distribution in the same host.}, number={4}, journal={GASTROENTEROLOGY}, author={Kim, SC and Tonkonogy, SL and Albright, CA and Tsang, J and Balish, EJ and Braun, J and Huycke, MM and Sartor, RB}, year={2005}, month={Apr}, pages={891–906} }
 @article{dieleman_hoentjen_qian_sprengers_tjwa_torres_torrice_sartor_tonkonogy_2004, title={Reduced ratio of protective versus proinflammatory cytokine responses to commensal bacteria in HLA-B27 transgenic rats}, volume={136}, ISSN={["1365-2249"]}, DOI={10.1111/j.1365-2249.2004.02410.x}, abstractNote={SUMMARY}, number={1}, journal={CLINICAL AND EXPERIMENTAL IMMUNOLOGY}, author={Dieleman, LA and Hoentjen, F and Qian, BF and Sprengers, D and Tjwa, E and Torres, MF and Torrice, CD and Sartor, RB and Tonkonogy, SL}, year={2004}, month={Apr}, pages={30–39} }
 @article{schultz_veltkamp_dieleman_grenther_wyrick_tonkonogy_sartor_2002, title={Lactobacillus plantarum 299V in the treatment and prevention of spontaneous colitis in interleukin-10-deficient mice}, volume={8}, ISSN={["1536-4844"]}, DOI={10.1097/00054725-200203000-00001}, abstractNote={Interleukin (IL)-10-deficient (IL-10−/−) mice develop colitis under specific pathogen-free (SPF) conditions and remain disease free if kept sterile (germ free [GF]). We used four different protocols that varied the time-points of oral administration of Lactobacillus plantarum 299v (L. plantarum) relative to colonization with SPF bacteria to determine whether L. plantarum could prevent and treat colitis induced by SPF bacteria in IL-10−/− mice and evaluated the effect of this probiotic organism on mucosal immune activation. Assessment of colitis included blinded histologic scores, measurements of secreted colonic immunoglobulin isotypes, IL-12 (p40 subunit), and interferon (IFN)-&ggr; production by anti-CD3-stimulated mesenteric lymph node cells. Treating SPF IL-10−/− mice with L. plantarum attenuated previously established colonic inflammation as manifested by decreased mucosal IL-12, IFN-&ggr;, and immunoglobulin G2a levels. Colonizing GF animals with L. plantarum and SPF flora simultaneously had no protective effects. Gnotobiotic IL-10−/− mice monoassociated with L. plantarum exhibited mild immune system activation but no colitis. Pretreatment of GF mice by colonization with L. plantarum, then exposure to SPF flora and continued probiotic therapy significantly decreased histologic colitis scores. These results demonstrate that L. plantarum can attenuate immune-mediated colitis and suggest a potential therapeutic role for this agent in clinical inflammatory bowel diseases.}, number={2}, journal={INFLAMMATORY BOWEL DISEASES}, author={Schultz, M and Veltkamp, C and Dieleman, LA and Grenther, WB and Wyrick, PB and Tonkonogy, SL and Sartor, RB}, year={2002}, month={Mar}, pages={71–80} }
 @article{veltkamp_tonkonogy_de jong_albright_grenther_balish_terhorst_sartor_2001, title={Continuous stimulation by normal luminal bacteria is essential for the development and perpetuation of colitis in Tg is an element of 26 mice}, volume={120}, ISSN={["1528-0012"]}, DOI={10.1053/gast.2001.22547}, abstractNote={BACKGROUND & AIMS
Normal resident bacteria are required for development of colitis in several rodent models. We determined whether bacterial stimulation is necessary for both induction and perpetuation of mucosal inflammation and T-cell activation in Tg(epsilon26) mice, in which transplantation of wild-type bone marrow (BM-->Tg(epsilon26)) causes colitis under specific pathogen-free (SPF) conditions.


METHODS
BM from (C57BL/6 X CBA/J) F1 mice was transplanted into germfree (GF) or SPF Tg(epsilon26) mice. Mesenteric lymph node (MLN) cells from these mice were then transferred into SPF or GF recipients. Colitis and activation of MLN cells were measured by histologic scores, membrane marker analysis, and intracellular cytokine staining. Cytokine secretion by MLN cells stimulated by anti-CD3 or by luminal or epithelial antigens was measured by ELISA.


RESULTS
Colitis did not develop when BM was transferred into GF recipient mice (BM-->GF Tg(epsilon26)). T lymphocytes that secreted interferon gamma upon activation were present in the MLN of BM-->GF Tg(epsilon26) mice, albeit in lower frequency than in control BM-->SPF Tg(epsilon26) mice. Furthermore, transfer of MLN cells from BM-->SPF Tg(epsilon26) mice into SPF Tg(epsilon26) recipients induced active colitis, but not if the same cells were transferred into GF Tg(epsilon26) recipients. Although CD4 T cells were detected in the colonic mucosa of GF recipients, no inflammation was observed for at least 31 weeks. In a reciprocal experiment, MLN cells from BM-->GF Tg(epsilon26) mice without colitis transferred disease to SPF Tg(epsilon26) recipients within 2-4 weeks.


CONCLUSIONS
Activated T cells are present in the mucosa of BM-->GF Tg(epsilon26) mice but are incapable of inducing disease unless colonic bacteria are present. Moreover, pathogenic T cells require the continuous presence of colonic bacteria to sustain colitis.}, number={4}, journal={GASTROENTEROLOGY}, author={Veltkamp, C and Tonkonogy, SL and De Jong, YP and Albright, C and Grenther, WB and Balish, E and Terhorst, C and Sartor, RB}, year={2001}, month={Mar}, pages={900–913} }
 @article{schultz_clarke_arnold_sartor_tonkonogy_2001, title={Disrupted B-lymphocyte development and survival in interleukin-2-deficient mice}, volume={104}, ISSN={["0019-2805"]}, DOI={10.1046/j.1365-2567.2001.01308.x}, abstractNote={Summary}, number={2}, journal={IMMUNOLOGY}, author={Schultz, M and Clarke, SH and Arnold, LW and Sartor, RB and Tonkonogy, SL}, year={2001}, month={Oct}, pages={127–134} }
 @article{dieleman_arends_tonkonogy_goerres_craft_grenther_sellon_balish_sartor_2000, title={Helicobacter hepaticus does not induce or potentiate colitis in interleukin-10-deficient mice}, volume={68}, ISSN={["1098-5522"]}, DOI={10.1128/IAI.68.9.5107-5113.2000}, abstractNote={ABSTRACT}, number={9}, journal={INFECTION AND IMMUNITY}, author={Dieleman, LA and Arends, A and Tonkonogy, SL and Goerres, MS and Craft, DW and Grenther, W and Sellon, RK and Balish, E and Sartor, RB}, year={2000}, month={Sep}, pages={5107–5113} }
 @article{ediriwickrema_tonkonogy_hammerberg_2000, title={Natural killer cell-dependent immunoglobulin G2a anti-bovine serum albumin (BSA) response elicited by high molecular weight dextran-BSA conjugates associated with dextran-mediated macrophage-natural killer cell interaction}, volume={101}, ISSN={["1365-2567"]}, DOI={10.1046/j.1365-2567.2000.00135.x}, abstractNote={Summary}, number={4}, journal={IMMUNOLOGY}, author={Ediriwickrema, CP and Tonkonogy, SL and Hammerberg, B}, year={2000}, month={Dec}, pages={474–483} }
 @article{de buysscher_tonkonogy_vaillancourt_barnes_2000, title={Quantitation of thymic and bursal lymphocytes populations in normal and PEMS affected turkeys}, volume={49}, number={2000}, journal={Proceedings of the ... Western Poultry Disease Conference}, author={De Buysscher, E.V. and Tonkonogy, S. and Vaillancourt, J.P. and Barnes, H.J.}, year={2000}, pages={95–97} }
 @article{schultz_tonkonogy_sellon_veltkamp_godfrey_kwon_grenther_balish_horak_sartor_1999, title={IL-2-deficient mice raised under germfree conditions develop delayed mild focal intestinal inflammation}, volume={276}, ISSN={["1522-1547"]}, DOI={10.1152/ajpgi.1999.276.6.g1461}, abstractNote={Interleukin-2 (IL-2) amplifies immune stimuli and influences B cell differentiation. IL-2-deficient mice spontaneously develop intestinal inflammation if raised under specific pathogen-free (SPF) conditions. We quantitatively determined the aggressiveness and kinetics of gastrointestinal and hepatic inflammation in the presence or absence of viable bacteria in IL-2-deficient mice. Breeding colonies were maintained under SPF and germfree (GF) conditions. Intestinal tissues, serum, and mesenteric lymph nodes were obtained from mice at different ages for blind histological scoring, immunoglobulin measurements, mucosal T cell infiltration, and cytokine secretion. GF IL-2 −/− mice developed mild, focal, and nonlethal intestinal inflammation with delayed onset, whereas the more aggressive inflammation in SPF IL-2 −/− mice led to their death between 28 and 32 wk. Periportal hepatic inflammation was equal in the presence or absence of bacterial colonization. Intestinal immunoglobulin secretion decreased significantly by 13 wk of age in IL-2 −/− mice in both GF and SPF environments. In contrast to other genetically engineered rodents, IL-2 −/− mice develop mild focal gastrointestinal and active portal tract inflammation in the absence of viable bacteria.}, number={6}, journal={AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY}, author={Schultz, M and Tonkonogy, SL and Sellon, RK and Veltkamp, C and Godfrey, VL and Kwon, J and Grenther, WB and Balish, E and Horak, I and Sartor, RB}, year={1999}, month={Jun}, pages={G1461–G1472} }
 @article{haynes_linton_eaton_tonkonogy_swain_1999, title={Interleukin 2, but not other common gamma chain-binding cytokines, can reverse the defect in generation of CD4 effector T cells from naive T cells of aged mice}, volume={190}, ISSN={["0022-1007"]}, DOI={10.1084/jem.190.7.1013}, abstractNote={Development of effectors from naive CD4 cells occurs in two stages. The early stage involves activation and limited proliferation in response to T cell receptor (TCR) stimulation by antigen and costimulatory antigen presenting cells, whereas the later stage involves proliferation and differentiation in response to growth factors. Using a TCR-transgenic (Tg+) model, we have examined the effect of aging on effector generation and studied the ability of γc signaling cytokines to reverse this effect. Our results indicate that responding naive CD4 cells from aged mice, compared with cells from young mice, make less interleukin (IL)-2, expand poorly between days 3 to 5, and give rise to fewer effectors with a less activated phenotype and reduced ability to produce cytokines. When exogenous IL-2 or other γc signaling cytokines are added during effector generation, the Tg+ cells from both young and aged mice proliferate vigorously. However, IL-4, IL-7, and IL-15 all fail to restore efficient effector production. Only effectors from aged mice generated in the presence of IL-2 are able to produce IL-2 in amounts equivalent to those produced by effectors generated from young mice, suggesting that the effect of aging on IL-2 production is reversible only in the presence of exogenous IL-2.}, number={7}, journal={JOURNAL OF EXPERIMENTAL MEDICINE}, author={Haynes, L and Linton, PJ and Eaton, SM and Tonkonogy, SL and Swain, SL}, year={1999}, month={Oct}, pages={1013–1023} }
 @article{bradley_malo_fong_tonkonogy_watson_1998, title={Blockade of both L-selectin and alpha(4) integrins abrogates naive CD4 cell trafficking and responses in gut-associated lymphoid organs}, volume={10}, ISSN={["0953-8178"]}, DOI={10.1093/intimm/10.7.961}, abstractNote={The recirculation of naive lymphocytes from blood to lymph that is initiated in high endothelial venules (HEV) of secondary lymphoid organs such as lymph nodes and Peyer's patches (PP) is regulated by multiple interactions of adhesion receptor/counter-receptor pairs involving both selectins and integrins. We showed previously that blocking of only L-selectin is sufficient to ablate trafficking of naive CD4 cells and the development of their responses in peripheral lymph nodes but not in PP where alpha4beta7 integrins are thought to primarily regulate entry. However, although antibody to alpha4 integrins partially inhibited homing of naive CD4 cells to PP and not to lymph nodes, there was no effect on the development primary responses in these tissues or spleens. Since previous studies indicate that both alpha4beta7 integrins and L-selectin regulate adhesion of naive cells to PP HEV, we examined the effect a blockade of both adhesion pathways on the recirculation of naive CD4 cells. There was no detectable homing of naive CD4 cells to PP or lymph nodes when interactions with both receptors were inhibited, resulting in a profound depletion of naive CD4 cells and loss of antigen responses in these sites. In contrast, increased numbers of naive CD4 cells and responses of higher magnitude were found in the spleen. The results demonstrate recirculation of naive CD4 cells through tissues where entry is controlled through HEV is essential for the local generation of primary responses.}, number={7}, journal={INTERNATIONAL IMMUNOLOGY}, author={Bradley, LM and Malo, ME and Fong, S and Tonkonogy, SL and Watson, SR}, year={1998}, month={Jul}, pages={961–968} }
 @article{sellon_tonkonogy_schultz_dieleman_grenther_balish_rennick_sartor_1998, title={Resident enteric bacteria are necessary for development of spontaneous colitis and immune system activation ininterleukin-10-deficient mice}, volume={66}, number={11}, journal={Infection and Immunity}, author={Sellon, R. K. and Tonkonogy, S. and Schultz, M. and Dieleman, L. A. and Grenther, W. and Balish, E. and Rennick, D. M. and Sartor, R. B.}, year={1998}, pages={5224–5231} }
 @article{bradley_malo_tonkonogy_watson_1997, title={L-selectin is not essential for naive CD4 cell trafficking or development of primary responses in Peyer's patches}, volume={27}, ISSN={["0014-2980"]}, DOI={10.1002/eji.1830270514}, abstractNote={Abstract}, number={5}, journal={EUROPEAN JOURNAL OF IMMUNOLOGY}, author={Bradley, LM and Malo, ME and Tonkonogy, SL and Watson, SR}, year={1997}, month={Mar}, pages={1140–1146} }
 @article{velez_tonkonogy_lichtman_cho_1997, title={Sensitized liposomes as an antigen delivery system for the stimulation of mucosal immunity}, volume={5}, ISSN={["1061-186X"]}, DOI={10.3109/10611869708995854}, abstractNote={This study was designed to exploit the ability of Peyer's patch M cells to recognize antigen-antibody complexes in the targeted delivery of a model antigen for the induction of mucosal immunity. Sensitized liposomes consisted of an entrapped model antigen, ovalbumin (OVA), and coated with unrelated antigen-antibody complexes. Sensitized liposomes were administered intrajejunally to mice either with or without monophosphoryl lipid A (MLA). Humoral immune responses were monitored in saliva, feces, serum, and bile. Mice which received sensitized liposomes showed up to 4-fold amounts of specific IgA in saliva, feces, and bile compared to controls. Transient increases in anti-OVA IgA and IgG were observed in serum. Formulations including MLA generated positive anti-OVA IgG responses in both serum and bile. In separate experiments, cell proliferation studies were performed with Peyer's patch lymphocytes harvested from mice immunized with OVA in either standard or sensitized liposomes. Lymphocytes from test mice receiving only sensitized liposomes proliferated in the presence of OVA, but not an unrelated antigen. Taken together, these results support the potential application of antigen-antibody complexes in the stimulation of mucosal immune responses and that MLA may play an important role in overcoming OVA tolerogenicity.}, number={1}, journal={JOURNAL OF DRUG TARGETING}, author={Velez, CN and Tonkonogy, SL and Lichtman, SN and Cho, MJ}, year={1997}, pages={15–24} }
 @misc{swain_bradley_croft_tonkonogy_atkins_weinberg_duncan_hedrick_dutton_huston_1991, title={HELPER T-CELL SUBSETS - PHENOTYPE, FUNCTION AND THE ROLE OF LYMPHOKINES IN REGULATING THEIR DEVELOPMENT}, volume={123}, ISSN={["0105-2896"]}, DOI={10.1111/j.1600-065X.1991.tb00608.x}, abstractNote={We have concentrated here on the lymphokines which might serve to regulate the different pathways of precursor development. We suggest that, as a result of antigenic stimulation, specific precursor cells both proliferate and become committed to develop into either an effector cell, a memory cell or an anergized cell. Anergy has not been dealt with in this review, but it is likely to be one of the options available. The development of an effector population takes 4-7 d (quite analogous to the time it takes for CTLp to become CTL and for resting B to become Ab-forming cells). The effector populations are large, generally IL-2R-positive cells. These cells have upregulated many adhesion molecule systems [e.g., Pgp-1, LFA-1 and ICAM-1 (Swain unpublished)], but downregulated the Mel-14 homing receptor. Effectors are ready to respond to APC such as specific B cells with a rapid synthesis and secretion of lymphokines. The effector population is then quickly downregulated, both by the turn off of lymphokine synthesis/secretion and possibly by its own suicide. This kind of pattern makes teleological sense since the cells making such high titers of lymphokines could have many potent pleitropic effects. It also seems to be the strategy employed in the generation of other terminally differentiated effectors (such as CTL and plasma cells). The requirement for restimulation and the requirement for direct and perhaps prolonged contact between the helper effector and the APC-B cell can be expected to help ensure that these lymphokines are localized (reviewed in Swain & Dutton 1987, Swain & Croft 1990) and effectively delivered to specific responding cells. We postulate that at the same time, or perhaps subsequent to this, another set of signals drives precursors to generate prememory cells. Our studies suggest these emerging memory cells may be phenotypically unique and we postulate that they are specialized to become a "long-lived" population of memory cells that will persist indefinitely as a protective population of increased frequency for the antigen encountered and which is also able to respond more rapidly and effectively. The greater effectiveness of the memory response would thus be due to dramatically increased frequency, to characteristic and stable changes in adhesion molecule expression and to the fact that, in addition to IL-2, resting memory cells also secrete at least low titers of IL-3, IL-4, IFN-gamma and other lymphokines upon initial restimulation.(ABSTRACT TRUNCATED AT 400 WORDS)}, journal={IMMUNOLOGICAL REVIEWS}, author={SWAIN, SL and BRADLEY, LM and CROFT, M and TONKONOGY, S and ATKINS, G and WEINBERG, AD and DUNCAN, DD and HEDRICK, SM and DUTTON, RW and HUSTON, G}, year={1991}, month={Oct}, pages={115–144} }