Carbohydrate moieties on sperm surface: physiological relevance.

OBJECTIVES: To study the cross-reactions between mouse monoclonal antisperm antibodies and somatic cells or bacteria, to identify the antigenic determinants responsible for such cross-reactions, and to correlate between the antibody function and determinant recognition.
DESIGN: Activities of monoclonal antibodies (mAbs) were characterized by immunosorbent assay of RIA technique; sperm epitopic characterization was performed in lectin-blocking and sugar competitive assays and correlated with functional assays.
SETTING: Procedures were performed in a university laboratory.
RESULTS: The extensive cross-reactivity between antigenic determinants of sperm, erythrocytes, and bacteria (but not bacterial deglycosylated lipopolysaccharides) was observed. The analytic procedures indicated predominant mAb reactions to carbohydrates such as fucose, galactose, mannose, N-acetylglucosamine and N-acetylgalactosamine. Approximately half of the 30 tested mAbs interfered in the functional assays, that is, sperm agglutination, immobilization, and zona-free penetration.
CONCLUSIONS: Sperm carbohydrates seem to induce antibody reactions to common antigenic determinant(s) present on gametes, somatic cells, and infectious agents. Thus molecular mimicry between bacteria and sperm can be a major factor inducing antisperm immunological reactions. Obtained antisperm mAbs, reacting to glycosylated epitopes, presented very strong properties in sperm agglutination and/or immobilization. This did not correlate with inhibiting properties of some antibodies in xenogeneic zona-free penetration test, that is, this assay possibly is not based on oligosaccharide mediation.