Inhibition of T suppressor cell expression by histamine type 2 (H₂) receptor antagonists

The effect of histamine type 2 (H₂) receptor antagonists, cimetidine and ranitidine, on the induction and expression of hapten-specific suppressor T cells was studied. The activity of DNBSO₃-induced suppressor cells was evaluated after adoptive transfer to naive syngeneic recipients. Treatment with cimetidine or ranitidine markedly inhibited suppressor T cell activity in a dose-related manner and enhanced the contact sensitivity response to DNFB. Both H₂ antagonists were effective in inhibiting the expression and, to a lesser extent, the induction of suppressor T cells. In contrast, norburimamide, a non-H₂ antagonist structurally related to cimetidine, was inactive. The relevance of these findings to the clinical observation of cimetidine-induced reversal of acquired tolerance to dinitrochlorobenzene in anergic patients is discussed.