MANNOSE-BINDING SITES ON HUMAN SPERMATOZOA AND SPERM MORPHOLOGY

Objective: To verify a possible association between the expression of sperm head mannose-binding sites and sperm morphology. Design: Prospec tive in vitro study, Setting: University-based sperm biology and andro logy laboratories. Participants: Twenty-seven fertile donors and 45 pa tients consulting for infertility. Interventions: D-mannose-binding si tes were identified using a fluoresceinated mannose-enriched bovine se rum albumin. Hoechst 33258 was included to confirm sperm viability and hypo-osmotic smelling test to assess plasma membrane integrity. Sperm morphology was judged by strict criteria and semen samples were class ified into three groups: normal (group N, >10% morphologically normal sperm, n = 27), good prognosis (group G, 5% to 10%, n = 23), or poor p rognosis (group P, less than or equal to 4%, n = 22), Results: Only vi able (Hoechst 33258 negative) spermatozoa with intact plasma membrane (hypo-osmotic swelling test positive) were considered in the evaluatio n of mannose-binding sites. The incidence of spermatozoa showing surfa ce mannose-binding sites was higher in the N group (48.1% +/- 1.9%; me an +/- SEM) than in the G (17.6% +/- 4.4%) or P (7.6% +/- 2.3%) groups . Total mannose-binding site expression and percentage of morphologica lly normal sperm showed a high positive correlation (r = 0.80). Conclu sion: Altered expression of mannose-binding sites, putative zona recep tors, may be one of the molecular defects causing decreased fertility in morphologically abnormal human sperm.