Association of MHC- and TCR-Like Immunoreactivity With Sperm Parameters in Human Semen

Since the expression of MHC and TCR molecules in murine semen was correlated to fertility, the present study focused in humans and inquired whether the complementarity of MHCs and TCRs could affect sperm quality through sperm morphology and motility.

Sixty sperm-donor samples engaged in assisted reproduction processes were examined as to sperm quality and ability to fertilization. Semen was examined for membrane MHC class I (MHCI), class II (MHCII), TCRαβ and TCRγδ molecule expression by immunofluorescence followed by electron/confocal microscopy or flow cytometry analysis, while the presence of their soluble forms in seminal plasma was examined using ELISA. TCRαβ-isolates from seminal plasma were submitted to SDS-PAGE analysis and ELISA.

All samples expressed membrane and soluble MHCI, MHCII, TCRαβ and TCRγδ molecules in spermatozoa and seminal plasma in a statistically significant one-way ANOVA repeated measure analysis. The expression was localized in spermatozoa head accompanied in most cases by tail staining, correlating with coiled-tail morphology. The distinction of samples into good-quality fertilizing, good-quality non-fertilizing and bad-quality non-fertilizing sperm showed statistically significant difference of MHCI, TCRαβ and TCRγδ in the fertilizing as compared to non-fertilizing groups. Evaluating already known parameters, significant increase of macrophage-migration inhibitory factor (MIF) in seminal plasma and decrease of nitric oxide were detected in fertilizing as compared to non-fertilizing samples. Seminal plasma-derived TCRαβ co-precipitated with MIF, resembling thus T-suppressor-Factor-1.

The results correlate polymorphic immune molecules in spermatozoa and seminal plasma with sperm morphology and motility, introducing novel parameters and research areas in sperm quality evaluation.