Effect of sperm-associated antibodies on the dynamics of sperm movement and on the acrosome reaction of human spermatozoa

Anti-sperm antibodies were eluted from the sperm cell fraction of autoimmune human ejaculates and transferred onto normal motile spermatozoa. The movement and the acrosomal status of these antibody-coated spermatozoa were evaluated after incubation in a capacitating medium. The amplitude of lateral head displacement (ALH) and the straight line velocity (VSL) were analyzed using an HTM automated motility analyser. Acrosomal loss was monitored by an FITC-conjugated lectin binding technique. During the 6-h incubation in BWW-BSA medium, antibody-free and antibody-coated spermatozoa exhibited significant changes of ALH and VSL distribution that evolved differently in the two populations. The dynamics of sperm movement in control spermatozoa were apparently modified by the presence of antibodies on the sperm membrane. The low percentage of spontaneous acrosomal loss obtained in control populations, even after 20 h of incubation, was not modified by the presence of antibodies on spermatozoa. However, the same antibodies decreased the acrosomal loss induced by a calcium ionophore after 3 h of incubation in capacitating conditions. These results suggest that sperm capacitation and acrosome reaction, considered as essential for successful fertilization, can be altered by anti-sperm antibodies present on human ejaculated spermatozoa.