Autoreactive T cells in mercury-induced autoimmunity. Demonstration by limiting dilution analysis

Mercuric chloride is responsible in Brown-Norway rats for an autoimmune disease that is autoregulated. Previous studies have shown that this agent induces T cell-dependent polyclonal B cell activation in these rats. Evidence has also been obtained for the existence of autoreactive T cells which play a role in the evolution of this process. In the present study, limiting dilution analysis was used to demonstrate that (a) frequent autoreactive T helper cells which proliferate in the presence of T cells from HgCl2-injected rats are present from day 4; (b) frequent auto-anti-Ia T helper cells which recognize normal B cells as well as B cells from HgCl2-injected rats appear from day 6; and (c) less frequent T suppressor cells which could play a role in autoregulation emerge from day 14.