title: Daily subcutaneous injections of peptide induce CD4+ CD25+ T regulatory cells.
abstract: Peptide immunotherapy is being explored to modulate varied disease states; however, the mechanism of action remains poorly understood. In this study, we investigated the ability of a subcutaneous peptide immunization schedule to induce of CD4(+) CD25(+) T regulatory cells. DO11.10 T cell receptor (TCR) transgenic mice on a Rag 2(-/-) background were injected subcutaneously with varied doses of purified ovalbumin (OVA(323-339)) peptide daily for 16 days. While these mice have no CD4(+) CD25(+) T regulatory cells, following this injection schedule up to 30% of the CD4(+) cells were found to express CD25. Real-time quantitative polymerase chain reaction (QPCR) analysis of the induced CD4(+) CD25(+) T cells revealed increased expression of forkhead box P3 (FoxP3), suggesting that these cells may have a regulatory function. Proliferation and suppression assays in vitro utilizing the induced CD4(+) CD25(+) T cells revealed a profound anergic phenotype in addition to potent suppressive capability. Importantly, co-injection of the induced CD4(+) CD25(+) T cells with 5,6-carboxy-succinimidyl-fluorescence-ester (CFSE)-labelled naive CD4(+) T cells (responder cells) into BALB/c recipient mice reduced proliferation and differentiation of the responder cells in response to challenge with OVA(323-339) peptide plus adjuvant. We conclude that repeated subcutaneous exposure to low-dose peptide leads to de novo induction of CD4(+) CD25(+) FoxP3(+) T regulatory cells with potent in vitro and in vivo suppressive capability, thereby suggesting that one mechanism of peptide immunotherapy appears to be induction of CD4(+) CD25(+) Foxp3(+) T regulatory cells.
authors.affiliation: Department of Pediatrics, University of Wisconsin, Madison, WI 53792-4108, USA.
authors.forename: P E
authors.initials: PE
authors.lastname: Dahlberg
authors.forename: J M
authors.initials: JM
authors.lastname: Schartner
authors.forename: A
authors.initials: A
authors.lastname: Timmel
authors.forename: C M
authors.initials: CM
authors.lastname: Seroogy
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D049109:Cell Proliferation; D004306:Dose-Response Relationship, Immunologic; D051858:Forkhead Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression; D007108:Immune Tolerance / Q000276:immunology; D007114:Immunization / Q000379:methods; D016130:Immunophenotyping; D007279:Injections, Subcutaneous; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis*; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D010446:Peptide Fragments; D012333:RNA, Messenger; D010047:Ovalbumin