Viral inhibition of lymphocyte mitogenesis. I. Evidence for the nonspecificity of the effect.

We have investigated the mechanism(s) whereby virus particles, when co-incubated with lymphocytes, are able to abrogate mitogen- and alloantigen-driven cell proliferation. Our data indicate that this inhibition is entirely nonspecific with regard to its induction; similar results can be obtained by using any of several different types of infectious virus particles or viruses whose infectivity had been destroyed by irradiation with ultraviolet light. Furthermore, we show that plasma membranes vesicles, which approximate viruses in size, and which are derived from normal cells, can also impede lymphocyte proliferative responsiveness. In the mixed lymphocyte culture (MLC) reaction, the inhibitory effect is apparently due to the action of viruseith virus can inhibit the mitogen-induced proliferation of resh syngeneic spleen cells, even if added to the latter at a ratio as low as 1:250. These results suggest that virus particles induce the activation of suppressor lymphocytes which in turn act on those cells which would otherwise be responsive in mitogenesis assays and in the MLC.