The G (Gross) leukemia antigen.

Abstract

Summary Antisera prepared in C57BL/6 mice by immunization with primary or transplanted spontaneous AKR leukemias were cytotoxic for certain C57BL/6 leukemias induced by Gross virus. Absorption studies indicated that these antisera were typing for the cellular antigen associated with Gross leukemia virus (G antigen), and that this antigen is distinct from the other known antigens associated with mouse leukemia. All leukemias induced by Gross virus were G+. The G antigen was found also in spontaneous leukemias of the AKR, AKR.K, C58 and F strains, and in normal lymphoid tissue from mice of these high-incidence strains. The G antigen was not present in the normal spleens of 15 low-incidence strains, but appeared in certain spontaneous and induced leukemias of these strains. Antigenic conversion (G-→ G+) occurs in the lymphoid cells of susceptible mice inoculated at birth with Gross virus, before the development of overt leukemia. No antigen, or very little antigen, was demonstrable in the progeny of crosses between AKR or C58 and C57BL/6, and the incidence of leukemia in both these hybrids is extremely low. Spleens of progeny from another cross, between C58 and C3Hf/Bi (which is highly susceptible to Gross virus), were G+. The presence of G antigen in spontaneous lymphoid leukemias, and the absence of antigens of the Friend-Moloney-Rauscher type, indicate that Gross virus rather than Moloney virus should be regarded as the mouse virus which exemplifies naturally occurring leukemogenic viruses.