Antigenic properties of a cell line from human prostate carcinoma (EB 33)

Evidence for tumor-specific transplantation antigens of human prostate carcinoma was gained by others from in vivo sensitization. The fact that these antigens have not been detected by in vitro methods prompted us to investigate whether EB 33 cells, originated from a human prostate carcinoma by one of us (F.H.S.), expressed these antigens. Using 3-M potassium chloride extracts of EB 33 cells for immunization of New Zealand white rabbits, we obtained xenogeneic antibodies. Further analysis of their specificity was achieved by indirect immunofluorescence and by measurement of their cytotoxicity in a [51Cr]-release test. Xenogeneic antibodies were cytotoxic for EB 33 cells. However, the extent of cell lysis depended on the passage number of EB 33 target cells, thus reflecting an alteration of the antigenicity of the EB 33 cell population during culture. Formation of nonspecific antibodies could be absorbed with HeLa cells. As HLA were not detectable on EB 33 cells, results obtained from absorption experiments with homogenates of normal and malignant prostate tissue may argue for organ-specific and tumor-related transplantation antigens on EB 33 cells.