Objective: To study by a triple stain technique the effect of sperm-immobilizing antibodies on the acrosome reaction of human spermatozoa.
Design: The spermatozoa were allowed to swim up and culture in a medium containing 7.5% (vol/vol) serum with sperm-immobilizing antibodies or control serum up to 6 hours. Sperm mobility was analyzed, and the percentage of live acrosome reacted spermatozoa was determined.
Setting: Samples were collected from patients referred to university hospital infertility clinics.
Materials: Serum samples were drawn from seven patients with sperm-immobilizing antibodies. All the sera were heat activated and stored at -40 degrees C until use. Semen samples were taken from two healthy donors.
Results: During culture for 6 hours, the percentage of live sperm showing the acrosome reaction increased significantly (P less than 0.01) in the control group but not in the sperm-immobilizing antibodies group. However, the inhibitory effect of sperm-immobilizing antibodies on the acrosome reaction was reversed when sperm was reincubated in medium with control serum (P less than 0.01).
Conclusions: Sperm-immobilizing antibodies block fertilization at least in part by inhibiting the acrosome reaction of human spermatozoa.