Immunity to Tumor-Associated Antigens in Vasectomized Men234

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Abstract
Leukocytes from 49 vasectomized and 57 age-matched nonvasectomized men were tested in the leukocyte adherence inhibition (LAI) assay for reactivity to sperm and various 3-M KCI human tumor extracts. Forty-four percent of the vasectomized men and 1 5% of the control group were reactive to the sperm antigen preparation (P≤0.03). Similarly, a significantly higher percentage of vasectomized men responded to 3 of 5 tumor extracts tested: melanoma I (34.7 vs. 15.8%, P≤0.04), squamous cell carcinoma (48.8 vs. 26.0%, P≤0.04), and breast carcinoma (19.5 vs. 4%, P≤0.04). Thirty percent of vasectomized versus 4% of the control group responded to more than two tumor antigens (P≤0.03). The degree of LAI reactivity to each tumor extract was highly correlated with degree of antisperm LAI reactivity, and the degree of LAI responsiveness to one of the melanoma extracts was significantly correlated with antisperm antibody titer as measured by the sperm-immobilization assay. Furthermore, nonresponsive leukocytes from the control population converted to tumor antigen-responsive when incubated with sera from vasectomized LAI-positive men. Data from this study indicated that a large percentage of vasectomized men with sperm immunity were responsive to tumor-associated antigens in the LAI test and that antisperm antibodies or other serum factors played a role in this response. These results and the evidence that most tumor antigen-responsive cancer patients also have serum antibodies that reacted with sperm suggested that vasectomized men and cancer patients frequently responded to immunologically cross-reactive antigenic determinants present on both sperm and tumor cells.