Complement-Inhibiting Activity of Human Seminal Plasma and Semen Quality

Abstract

Human seminal plasma (SP) contains potent complement inhibitors. This study examined the complement-inhibiting activity of individual SP samples from 118 patients with infertility and analyzed them in relation to various semen parameters. When 25% complement-inhibiting activity was considered the cut off value, less than 1 SD unit from the mean percentage of inhibition of SP samples with normal semen quality, 32 samples (27%) showed low inhibiting activity. Among the lower group, incidences of patients with asthenozoospermia (66%) and oligozoospermia (31%) were significantly (p < .01) higher than those (36 and 10%) in the group whose SP showed significant inhibiting activity. Partial characterization revealed that the component responsible for complement inhibition was heat labile, trypsin resistant, high molecular weight (>10 kD) glycoprotein that can inhibit alternative as well as classical complement pathways. Furthermore, since in the majority of SP samples the anticomplementary activity was blocked by monoclonal antibody against membrane cofactor protein (MCP) or decay accelerating factor (DAF), the complement-inhibiting factors that were identified are likely to be MCP and/or DAF, which are known to be present in human SP. These results suggest that complement-regulatory proteins in SP such as MCP and DAF may protect sperm cells against complement attack in the male reproductive tract.

Asthenozoospermia: Analysis of a Large Population

“…It is the secretion of the major accessory glands, prostate, and seminal vesicles. In addition to participation of seminal vesicles in the production of the vaginal plug, seminal vesicle secretions influence the metabolism, motility [11], and surface properties of sperm, and suppress immunocompetence. Although many studies on seminal plasma have been done, including some related to its role in immunology [13,15] and its biophysical properties [18], further research should be carried out to clarify its involvement in sperm motility.…”

High level of α1‐acid glycoprotein in human seminal plasma is associated with high branching and expression of Lewisa groups on its glycans: Supporting evidence for a prostatic origin

“…Hundred percent activity corresponds to 0.23 nmol min À1 ml À1 in Group 1 and 0.27 nmol min À1 ml À1 in Group 2; R, O-(CH 2 ) 8 -COOCH 3 . an important role in fertility [36][37][38]. Therefore, future studies must be performed to investigate the functional implications of the type of glycosylation found on AGP in seminal plasma.…”

The Male Role in Pregnancy Loss and Embryo Implantation Failure

“…Whether this is relevant for human pregnancies, it is still a matter of debate. Furthermore, other factors present in seminal plasma were reported to influence immune responses, for instance, the soluble p55 TNF-α receptor known to inhibit TNFmediated cytotoxicity (Liabakk et al 1993), spermine which impairs proliferation of NK cells and T lymphocytes (Evans et al 1995), and inhibitors of the complement system Chowdhury et al 1996). Finally, prostaglandins were suggested to prevent lymphocyte proliferation, NK cell activity, and secretion of pro-inflammatory cytokines (Kelly 1995;.…”