Immunobiology of carcinoma of the prostate

Limited evidence suggests that prostatic cancer cells express antigens that are immunogenic in the host. Some of these tumor-associated antigens are fetal antigens and others may be oncogenic viral-induced tumor antigens. In addition, both benign and malignant prostatic epithelial cells produce an antigenically distinctive form of acid phosphatase, but it is unknown whether acid phosphatase can function as a target for cytotoxic mechanisms. There is ample evidence that host cell-mediated immunologic activity is depressed in many prostatic cancer patients. The mechanisms underlying these impairments are unclear, but a number of factors has been implicated including uncharacterized 'serum blockers', alpha-2 globulins, and circulating antigen-antibody complexes. Endocrine manipulations can also alter host immune mechanisms. There is some evidence to suggest that host immune competence correlates inversely with tumor progression in patients who have relapsed after endocrine therapy. Immunotherapy for prostatic cancer has not been adequately studied. There have been a few inconclusive attempts at active immunotherapy using bacille Calmette Guerin and cryosurgery and virtually no attempts at passive immunotherapy. The future prospects for immunology as a useful tool in the management of prostatic cancer patients are discussed.