PARAMAGNETIC BEADS COATED WITH PISUM-SATIVUM AGGLUTININ BIND TO HUMANSPERMATOZOA UNDERGOING THE ACROSOME REACTION

For the evaluation of sperm functions it is important to assess the ac rosome reaction after induction with various stimuli. Acrosome reactio n tests normally include the capacitation of spermatozoa, treatment wi th an inducer, and detection of acrosomal loss by dyes, lectins or ant ibodies. Since most of these methods are time-consuming or require exp ensive equipment, paramagnetic beads coated with Pisum sativum aggluti nin (PSA) were investigated for their usefulness in facilitating the d etection of human sperm acrosome reaction. Binding of PSA beads to the acrosomal region increased significantly after incubation of capacita ted spermatozoa with 10 mu M A23187 (20.3 +/- 6.7% [mean +/- SD, absol ute binding], n= 21), 1 mM dibutyryladenosine cyclic monophosphate (17 .1 +/- 8.5%, n=25) and 10 mM phorbol myristate acetate (21.1 +/- 12.5% , n=10). Bead binding was significantly reduced by preincubation with a protein kinase inhibitor. Beads bound to Concanavalin A (ConA) were also attached to the acrosomal region after induction of the acrosome reaction by A23187 or dbcAMP, but a lower number of spermatozoa were b ound to ConA-beads than to PSA beads. Pre-treatment of spermatozoa wit h alpha-methyl-D-mannoside before addition of the PSA beads markedly d ecreased bead binding, which indicates its mannose-specificity. Electr on microscopic examinations demonstrated that PSA beads mainly bound t o membrane structures of spermatozoa that were undergoing, but had not completed the acrosome reaction.