Suppression of experimental allergic encephalomyelitis in rats by suppressor factor from a permanent T cell line.

An antigen non-specific suppressor factor (SF4) produced by a permanent mouse T cell line inhibits the mitogen- and antigen-induced proliferation of cells in vitro. The suppression of immune response is not restricted by interspecies barrier. Administration of the SF4 factor in vivo had a significant suppressive effect on the induction and manifestation of experimental allergic encephalomyelitis (EAE) in rats. Rats treated with SF4 factor, the first dose being injected on the day of EAE induction, had no clinical manifestations or developed only mild clinical signs of EAE. Administration of the SF4 starting on day 4 after EAE induction, when the immune system had been activated, depressed the course of EAE. The results obtained in this model autoimmune disease indicate that the described suppressor factor is active in vivo and that it may be used to depress the autoaggressive immune reactions.