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

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.