Limitations and utility of a cytolytic assay for measuring simian virus 40-induced cell surface antigens

Antisera were produced against an SV40-transformed cell line in the syngeneic AL/N mouse. With a microcytolytic assay, the specificity of antisera produced by various immunization schedules and their ability to lyse numerous SV40-transformed cell lines were determined. Various AL/N mouse cell lines, newly transformed by SV40 and cloned, were found to be lysed by the antisera. When tumors were induced by SV40-transformed cells in the syngeneic mouse and cell lines were reestablished from tumors and such procedures were repeated, the susceptibility to serum-mediated cytolysis of the sublines was the same as that of the original SV40-transformed cell line, in spite of differences in tumorigenicity. Polyoma virus-transformed AL/N cell lines were also lysed while AL/N embryo cells, untransformed by SV40 or by polyoma, were not. SV40-transformed T-antigen-positive BALB/c mouse or hamster cell lines or a T-antigen-positive tissue cultured human cell were also resistant to lysis. A competition type of microassay demonstrated specific inhibition of the serum-mediated cytolysis by all of the SV40 T-antigen-positive cell lines tested. Thus, the lack of lysis of cells did not necessarily indicate the absence of SV40-induced surface antigens. The polyoma-transformed AL/N cell line also inhibited the antisera, but to a lesser extent, suggesting the possibility that SV40 and polyoma virus transformation may result in the appearance of partially common cell surface antigens.