Viral abrogation of lymphocyte mitogenesis: induction of a soluble factor inhibitory to cellular proliferation.

PHA and Con A-driven mitogenesis of mouse C3H lymphocytes can be inhibited by co-incubation with a variety of different virus particles. These effects appear independent of infection, and can be obtained using UV-inactivated virus. Viruses may be added to spleen cell cultures as late as 46 h after co-incubation with mitogen, and still achieve significant inhibition of proliferative responsiveness. The described inhibition is apparently mediated, in part at least, by a soluble factor which is induced in splenic cultures following interaction with virus particles. This factor is apparently a product of macrophages. It does not posess interferon activity, but does have the ability to inhibit lectin- and alloantigen-driven mitogenesis, as measured in fresh cultures of splenic lymphocytes and in the mixed lymphocyte culture (MLC) reaction, respectively. Moreover, addition of virus to splenic cultures can apparently activate suppressor lymphocytes with the ability to inhibit proliferative responsiveness of fresh lymphocyte suspensions in the presence of Con A.