[Ability of virus SV40 T-antigen to simulate the effect of specific T lymphocyte growth factor--interleukin-2].

: The entering of T-lymphocytes into the DNA-synthesizing phase was marked by three consecutive signals, i.e., antigenic influence, interleukin-2, a specific T-lymphocyte cell growth factor, and non-specific serum growth-promoting factors, in the first place, transferrin. This system was used for the study of effects of virus SV40 T-antigen on cell mitotic cycle. Purified T-antigen was injected consecutively into T-lymphocytes, using erythrocyte ghost vesicles instead of one of control signals. It was shown that T-antigen cannot simulate the antigenic response but simulates the effect of interleukin-2, a specific growth-promoting factor. However, both normally proliferating T-lymphocytes and T-antigen-induced lymphocytes showed an absolute requirement for transferrin and, apparently, for other nonspecific growth-promoting factors. It was assumed that the polymorphism of tumours induced by papovaviruses is determined by the ability of their "early" proteins to imitate the effects of their specific growth-promoting factors on the cells.