Experimental myositis in rats. II. The sensitivity of spleen cells to syngeneic muscle antigen.

The transformation responses to a syngeneic muscle homogenate of spleen cells, lymph node cells and blood lymphocytes have been studied in rats with allergic myositis. Significantly increased responses to muscle were obtained only for spleen cells from rats which had received two or more immunizing injections of heterologous muscle with Freund's complete adjuvant. Other populations of lymphoid cells which had previously been shown to be capable of transferring the disease did not show significant transformation responses to muscle. Increased responses in spleen cells were obtained using a supernatant ultracentrifugal fraction as well as a whole muscle homogenate. Fractionation of the antigen showed blast stimulating activity to be present in fractions of differing molecular size, suggesting that the antigen(s) responsible may be present in polymeric form or may be bound to molecules of varying molecular size.