Specificity of cell membrane antigens in prostate cancer

Male CD2F₁ mice bearing an MCAM-7 transplant in the right leg underwent surgical excision of the tumor and showed specific resistance to subsequent challenges with that identical tumor line. An in vivo response to tumor-specific antigens (MCAM-7 antigen) solubilized by hypertonic potassium chloride was measured by 24-hour footpad swelling response in male CD2F₁ mice immunized to the tumor from which the antigens were extracted. These observations suggested that the transplantable MCAM-7 fibrosarcoma could produce immunity toward the solubilized MCAM-7 tumor antigens and that this tumor immunity could be measured by footpad swelling response to injection of the solubilized antigens, an indication of cell-mediated immunity. The footpad swelling response was also monitored in relation to the extent of tumor growth. Similar techniques have been applied to patients bearing adenocarcinoma of the prostate for whom skin testing was substituted for the measurement of footpad swelling in animals. Four of 10 patients, who had known prostate carcinoma and were given intradermal injections of soluble tumor antigens extracted from their tumors, exhibited a cutaneous, delayed type hypersensitivity response to the injected autologous tumor extracts. No positive reactions were observed in response to solubilized components of control tissues, including BPH. These observations suggest that some patients bearing adenocarcinoma of the prostate can exhibit an immunologic response to specific antigens present in their neoplasms.