Complement-fixing antigen of human sarcomas.

Further investigation of the humoral immune responses of patients with sarcoma to their tumors revealed a sarcoma-associated antigen that was readily detected by complement fixation. Circulating levels of antibody to this antigen, tentatively labeled S3, rose markedly after surgical removal of the tumor. Antibody to S3, as to S1 and S2, was highly prevalent in patients with various malignant tumors other than sarcoma.