Low expression of adhesion molecules and matrix proteins in patients showing poor penetration in zona-free hamster oocytes.

The expression of adhesion molecules and matrix proteins by human spermatozoa as well as their binding to and penetration of zona-free hamster eggs were investigated in 17 patients by means of flow cytometry. Both binding and penetration of hamster oocytes and expression of alpha- and beta-chains of beta 1, beta 3 and beta 4 integrins were determined before and after induction of the acrosome reaction. The expression of the integrin ligands, fibronectin and laminin were also analysed. Significant differences in the expression of very late antigen (VLA) integrins, VLA alpha 4-chain (CD49d), the classical fibronectin receptor VLA alpha 5-chain (CD49e), leukocyte function-associated molecule-3 (LFA-3; CD58) and fibronectin were observed between patients showing good (> 10%) or poor (< 10%) penetration in the sperm penetration assay (P = 0.0068). It is concluded that these adhesion molecules are intimately involved in the sperm-oolemma interaction. Since no differences were observed in either spermiogram parameters or the percentages of acrosome-reacted spermatozoa in the two groups, sperm-oolemma binding and penetration should be regarded as discrete parameters of sperm function.