Cell surface antigens associated with murine leukemia virus: definition of the GL and GT antigenic systems.

Two new serological specificities were identified on the surface of murine leukemia virus (MuLV)-infected cells by direct and absorption immunofluorescence tests. Both antigens were detected with antisera prepared in rats that were growing transplants of syngenic MuLV-induced leukemias. Antigen G(L) was defined with the AKR leukemia K36 as the test cell; antigen G(T) was defined with the W/Fu leukemia C58(NT)D as the test cell. G(L) and G(T) antigens were serologically and genetically independent of the MuLV-induced Gross and G(IX) cell-surface antigens. G(L) and G(T) antigens were found in normal lymphoid cells of mice from high-leukemic strains, but not in lymphoid tissues of mice from most low-leukemic strains. Tumors and leukemias of mice of low-leukemic strains often were G(L) and G(T) positive. Similarly, infection of normal cells with MuLV resulted in expression of G(L) and G(T). With ferritin-labeled antibody the G(L) and G(T) antigens were observed on virus-free segments of the cell surface. Genetically, G(L) and G(T) antigens were each controlled by two dominant unlinked genes in AKR mice; these same antigens were each controlled by three or more dominant unlinked genes in C58 mice. Penetrance of G(L) and G(T) regulatory genes was dependent upon the Fv-1 genotype of the host. Expression of G(L) antigen was closely associated with virus production, whereas expression of G(T) antigen was less closely associated.