Effect of human seminal plasma on tumour-associated immunity in patients with adenocarcinoma of the prostate.

Tumour-associated antigen-induced leukocyte adherence inhibition has been used as an in vitro criterion for evaluating the effect of normal human seminal plasma (HuSePl) on cell-mediated anti-tumour-associated immunity in patients with adenocarcinoma of the prostate. Significant (P < 0.01) suppression from the reactivity obtained with unincubated patients' leukocytes to allogenic extracts of malignant prostatic tissue ranging from 16 to 80% was observed in 22 of 25 patients (88%) following preincubation of their leukocytes with HuSePl. The observed suppression of tumour-associated immunity in the presence of HuSePl provides further evidence for the suppressive activity of SePl on a range of in vitro immune response in normal murine and human hosts. It is suggested that these results, together with those demonstrating experimental prostatic cancer from sensitization by spermatozoa and the relationship of prostatic cancer to repression of sexual activity, provide preliminary evidence of the possible participation of SePl as contributory to the natural history of prostatic cancer.