The initial phase of an immune response functions to activate regulatory T cells.
An early reaction of CD4(+) T lymphocytes to Ag is the production of cytokines, notably IL-2. To detect cytokine-dependent responses, naive Ag-specific T cells were stimulated in vivo and the presence of phosphorylated STAT5 molecules was used to identify the cell populations responding to IL-2. Within hours of T cell priming, IL-2-dependent STAT5 phosphorylation occurred primarily in Foxp3(+) regulatory T cells. In contrast, the Ag-specific T cells received STAT5 signals only after repeated Ag exposure or memory differentiation. Regulatory T cells receiving IL-2 signals proliferated and developed enhanced suppressive activity. These results indicate that one of the earliest events in a T cell response is the activation of endogenous regulatory cells, potentially to prevent autoimmunity.
O'Gorman
William E
WE
Department of Microbiology and Immunology, Stanford University School of Medicine, CA 94305, USA.
Dooms
Hans
H
Thorne
Steve H
SH
Kuswanto
Wilson F
WF
Simonds
Erin F
EF
Krutzik
Peter O
PO
Nolan
Garry P
GP
Abbas
Abul K
AK
D000818:Animals; D049109:Cell Proliferation; D007376:Interleukin-2 / Q000096:biosynthesis / Q000502:physiology; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010766:Phosphorylation; D016192:Resting Phase, Cell Cycle / Q000235:genetics / Q000276:immunology; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000821:virology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism* / Q000821:virology; D013997:Time Factors; D014616:Vaccinia virus / Q000276:immunology
D007376:Interleukin-2; D050799:STAT5 Transcription Factor