Effect of Staphylococcal Enterotoxin B-Induced Anergy on Cytokine Gene Expression: Anergy-Sensitive and Resistant mRNA Expression

Abstract

We examined the effect of staphylococccal enterotoxin B (SEB)-induced anergy on expression of six different cytokine genes in T cells restimulated with SEB in vitro. We found that although IL-2, IL-3, and IL-4 mRNA levels are substantially reduced in anergic T cells, mRNAs for IL-6, IL-10, IFN-γ, and TNF-α are expressed normally. Thus, there appeared both anergy-sensitive and resistant cytokine mRNA expression in restimulated anergic T cells. The same pattern of cytokine mRNA responses was observed in anergic CD4⁺ T cells, indicating that the preferential induction of anergy in Thl-like cells is not evident in this in vivo model. Employing TCR Vβ8.2 transgenic mice in which almost all T cells become anergic, we found that the TCR/CD3 complex can transduce both anergy-sensitive and resistant signals. Furthermore, a series of experiments using FK506, A23187, and PMA suggests that signals between TCR and activation of calcineurin and protein kinase C may be blocked in anergic T cells. This is supported by our gel mobility shift assays indicating that calcineurin and/or PMA-inducible NF-ATp, OAP⁴⁰, and AP-1, but not calcineurin-independent Oct-2, are repressed in anergic spleen T cells upon restimulation with SEB. Taken together, these results suggest that, among signals elicited by stimulation of TCR with SEB, a Ca²⁺/calcineurin—NF-ATp pathway and other signals, including protein kinase C, are repressed in anergic T cells upstream of their activation, which are essential for the cytokine mRNA expression of the anergy-sensitive type but are dispensible for those of the anergy-resistant type.