Decreased suppression of antibody-dependent cellular cytotoxicity by seminal plasma in unexplained infertility

Abstract

Objective: To determine whether seminal plasma (SP) from unexplained infertile males has different suppressive activity on antibody-dependent cellular cytotoxicity (ADCC) than SP from fertile males or SP from males of couples with known infertility factor. Design: Comparative clinical/experimental study. Setting: In vitro fertilization program in a university hospital and a hospital research laboratory. Patient(s): A total of 245 SP samples from 174 infertile and 16 fertile couples were compared. Intervention(s): SP suppression of ADCC was measured by using human 51chromium-labeled red blood cells (RBC), sensitized with IgG-rabbit-anti-human-RBC as targets and peripheral blood lymphocytes as effector cells. Main Outcome Measure(s): Suppressive activity of each sample was determined by calculating 51Cr-release in the presence and absence of SP. Result(s): When analyzed with respect to sperm number, motility, and morphology, suppressive activities of samples with normal semen analyses ( n = 142) were significantly higher ( x = 37% ± 14%) than suppressive activities of abnormal samples ( n = 103; x = 32% ± 13%). There was no strong correlation of suppressive activity to other semen parameters. Within the andrologically normal males, SP from the unexplained infertile couples ( n = 15) showed significantly lower suppressive activity ( x = 24% ± 11%) compared with the SP from fertile males ( n = 16; x = 35% ± 13%) and from couples with female infertility factor ( n = 65; x = 39% ± 14%). Conclusion(s): Loss of suppressive activity is associated with unexplained infertility, even in male patients who previously were considered normal by traditional methods of semen analysis.