Release of protein bound sialic acid from fibrosarcoma cells after cis-dichlorodiammine platinum (II) treatment: the possible role in tumor regression.

Cis-dichlorodiammine platinum (II) (cisplatin) has been successfully used in experimental immunotherapy of syngeneic transplantable fibrosarcoma in mice. Incubation of fibrosarcoma cells with cisplatin in vitro causes release of sialic acid from tumor cells. The estimation of sialic acid in the supernatant have shown a difference in the release of sialic acid from the tumor cells with different concentrations of cisplatin. The removal of sialic acid from fibrosarcoma cells after cisplatin treatment suggests a possible exposure of certain antigenic sites on the tumor cell surfaces. Such membrane changes may be responsible for the increased antigenicity of fibrosarcoma cells.