Forssman antigen in BK virus-induced tumor cell lines

A complement-mediated microcytotoxicity assay was used to detect Forssman antigen in BK virus (BKV)-induced tumor cells. BKT-1B, a transplantable hamster tumor cell line, contained Forssman antigen as did some other hamster cell lines tested for comparison. A rat embryo cell line transformed by BKV in vitro was negative for Forssman antigen. The presence of forssman antigen in hamster cell lines was confirmed by absorption experiments of rabbit forssman antiserum with the tumor cells, although in quantitative terms the results obtained by the two techniques were somewhat different. Immunization of rabbits with tumor cells also induced production of Forssman antibody; a much weaker response was observed in hamsters and rats.