Uncoupling of cytokine mRNA expression and protein secretion during the induction phase of T cell anergy.

Abstract

The CD4+ T cell clone HA1.7 may be made specifically nonresponsive, or anergic, to its cognate Ag, an influenza hemagglutinin peptide (HA), by pretreatment with the superantigen Staphylococcus aureus enterotoxin B or with high concentrations of HA itself. We compare the patterns of mRNA expression and protein production of selected T cell cytokines during the first 24 h after treatments that induce anergy in HA1.7 and during the same period after treatments that simulate normal cellular activation. The cytokines examined include TNF-alpha, IL-8/neutrophil activating protein-1 and the RANTES/SIS cytokines, a family of small secreted proteins with inflammatory and potential antiproliferative and leukocyte regulating activities. Messenger RNA for TNF-alpha, human MIP-1 alpha, human MIP-1 beta, and IL-8 are all induced during the development of clonal anergy in HA1.7, and these levels are significantly higher than those seen during activation of the clone using an anti-CD3 antibody and IL-2. These high levels of mRNA also persist longer than those seen after anti-CD3 and IL-2 activation. However, the increased levels of mRNA are not typically accompanied by increased protein secretion. In all cases but one, the amount of cytokine secreted by HA1.7 cells was greater after anti-CD3 and IL-2 treatments than after anergy-inducing treatments. Thus, the induction of T cell anergy in HA1.7 does not appear to require a general inhibition of T cell cytokine mRNA expression, and, in fact, anergy treatments appear to superinduce certain cytokine transcripts, but anergy-specific posttranscriptional mechanisms may exist by which cytokine release is regulated.