Immunologic studies of prostatic cancer using the R3327 rat model.

We report herein on the destruction by cryosurgery of the Dunning R3327 adenocarcinoma grown in the prostate. Tumors less than 1,000 mm.3 were destroyed by a single freezing procedure within 2 to 4 weeks, whereas tumors greater than 1,000 mm.3 could not be destroyed completely. We also have been able to demonstrate antibody and cellular immune responses to antigens on the R3327 cells. Species, organ and tumor specific antigens were identified by xenogeneic antiserum produced in the rabbit, while major and minor antigens were identified by alloantisera produced in the rat. Tumor antigens were characterized by a variety of in vitro and in vivo immune responses. In addition to the rabbit xenoantisera used in cytotoxicity assays, mixed lymphocyte tumor interaction produced a demonstrable in vitro immune response, lymphocytes from rats immunized with tumor cells were cytotoxic to radiolabeled tumor cells in culture, rats immunized with tumor cells in adjuvant demonstrated protection against subsequent challenge and immunological stimulation of lymph nodes draining the site of tumor cell inoculation was demonstrated by an increase in lymphocyte trapping. Clearing, the R3327 tumor system in the rat is suitable for immunological studies of prostatic cancer.