The presence of complement fixing antibodies to the avian group-specific ("gs") sarcoma-leukosis antigen in the human population and in cancer patients.

Antibodies to the avian group-specific "gs" sarcoma-leukosis antigen were made evident by complement fixation reaction in human sera collected from apparently healthy subjects and from patients with different forms of cancer and non-neoplastic diseases. The number of sera investigated was of 2,123. The possible mechanisms that might account for this paraimmune response of the human organism and the prospects of developing prophylactic steps against cancer are discussed.