Anti-squamous tumor antibodies in patients with squamous cell carcinoma.

Patients with advanced squamous cell carcinomas were shown to have serum antibodies directed towards cultured squamous tumor cells as shown by quantitative membrane immunofluorescence. The sera of these same patients did not react with a variety of other cultured tumor cells. Serum obtained from normals or from patients with other forms of cancer (transitional cell carcinoma, adenocarcinoma, and melanoma) did not give positive reactions. When the sera of squamous carcinoma patients were chromatographed on Sephadex G-150, tumor-reactive antibodies were recovered solely in the 19 S fraction, suggesting immunoglobulin M as the immunoglobulin isotype involved. Identification of the squamous tumor cell-reactive immunoglobulin as ijmunoglobulin M was confirmed by quantitative immunofluorescence with the use of class monospecific antisera to human immunoglobulins.