T cell stimulation in the absence of exogenous antigen: a T cell signal is induced by both MHC-dependent and -independent mechanisms.
Mature T cells residing in peripheral lymphoid organs have frequent contact with antigen presenting cells (APC). Such contact may be required for T cell survival, but the degree to which signals in mature T cells are induced by TCR recognition of self peptide/MHC complexes is unclear. We have used induction of the early growth response gene 1 (Egr1) as an indicator of signal transduction in 3.L2 (I-Ek-restricted) T cells interacting with APC in the absence of exogenous antigen. The data show that Egr1 can be induced in 3.L2 T cells by TCR recognition of self peptides presented by I-Ek. However, a more transient induction of Egr1 can be induced in 3.L2 T cells interacting with dendritic cells derived from class II/beta2m double-deficient mice. Egr1 induction after T cell-APC contact was also observed in a freshly isolated polyclonal CD4 T cell population. The data suggest that self peptide/MHC recognition by the TCR induces a signal in T cells and that dendritic cells can also induce a more transient T cell signal by an MHC-independent mechanism.
Department of Biology, Georgia State University, Atlanta, GA, USA.
Matthew
M
Bettini
Hongkang
H
Xi
Gilbert J
GJ
Kersh
D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology; D000941:Antigens / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D006649:Histocompatibility Antigens / Q000502:physiology*; D017874:Immediate-Early Proteins; D008285:Major Histocompatibility Complex / Q000502:physiology; D051379:Mice; D010455:Peptides / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D013601:T-Lymphocytes / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*
D000941:Antigens; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D006649:Histocompatibility Antigens; D017874:Immediate-Early Proteins; D010455:Peptides; D012333:RNA, Messenger; D014157:Transcription Factors