Localization of antibodies on spermatozoa and sperm movement characteristics are good predictors of in vitro fertilization success in cases of male autoimmune infertility

Objective To define sperm factors related to in vitro fertilization (IVF) failure in cases of antisperm autoimmunity. Design A detailed analysis of sperm morphology, movement characteristics, acrosomal function, and antibody binding was performed on the sperm population selected on a discontinuous two-layer Percoll gradient and used for IVF. The results were compared retrospectively between fertilizing (n=13) and nonfertilizing (n=11) sperm populations. Patients Twenty-one infertile couples undergoing 24 cycles of IVF treatment because of antisperm autoimmunity were included in this study. Results Fertilizing and nonfertilizing sperm populations were not different with respect to the percentage of motility, the normal morphology, the multiple anomalies index, the acrosome abnormalities, and the spontaneous or induced acrosome reaction. If the proportion of spermatozoa coated with either immunoglobulin (Ig)A or IgG antibodies was similar in the two groups, their localization was often different: antibodies were mainly on the sperm heads in the cases of fertilization failure. There were significant differences between fertilizing and nonfertilizing sperm samples in several movement parameters. Among them, the amplitude of lateral head displacement (ALH) was the most significantly correlated with fertilization success. Finally, spermatozoa were poorly bound to the zona pellucida (ZP) when fertilization failed, whereas high numbers of spermatozoa were attached to the ZP when fertilization occurred. Conclusion Fertilization failure in patients with antisperm antibodies may be the result of several factors in which the impact of the antibodies on the membrane function play a critical role. Movement parameters, particularly the ALH and the localization of antibodies on migrated spermatozoa could predict the IVF failure or success more accurately than the proportion of antibody-coated spermatozoa in the inseminated populations. The fertilization failure was associated with an incapacity of spermatozoa to bind to ZP.