Expression of D-mannose binding sites on human spermatozoa: comparison of fertile donors and infertile patients.

OBJECTIVE

The hypothesis that defective expression of D-mannose binding sites (presumptive elements of the sperm-zona pellucida binding mechanism) is related to male infertility was tested.

DESIGN

Experiments were performed on sperm samples from two groups of men classified, respectively, as fertile and infertile, based on their reproductive history.

SETTING

The study was carried out in an andrologic laboratory of a University Hospital.

PATIENTS, PARTICIPANTS: Fertile men were healthy sperm donors; infertile men were patients with fertility problems.

INTERVENTIONS

D-mannose binding sites were visualized by fluorescence microscopy using a mannosylated neoglycoprotein probe.

MAIN OUTCOME MEASURES

The hypothesis as reported in the objective section was formulated before data collection and was not modified thereafter.

RESULTS

Sperm from fertile men displayed a characteristic pattern of changes in the expression of D-mannose binding sites during in vitro capacitation. This pattern was altered in sperm from infertile men.

CONCLUSIONS

If the relationship between defective expression of D-mannose binding sites and decreased sperm fertilizing ability is validated by parallel tests of sperm-zona binding, it may be used for development of chemical tests replacing the current ones using human zonae pellucidae.