HIGH-LEVELS OF SPERM-ASSOCIATED ANTIBODIES IMPAIR HUMAN SPERM-OOLEMMAINTERACTION AFTER SUBZONAL INSEMINATION

Objective: To investigate the impact of sperm-associated antibodies in the fertilization process beyond the zona pellucida in human oocytes. Design: Subzonal insemination (SUZI) was performed with antibody-coat ed spermatozoa from patients with autoimmune infertility. Sperm parame ters and antibody binding were analyzed after Percoll selection and we re compared with SUZI outcome. Patients: Patients (n = 29) with an imm unobead test higher than 60% for immunoglobulin (Ig)G, IgA, or both cl asses were included in the study (38 attempts). Twenty-six patients ha d previous IVF failures, and the semen characteristics for three were unsuitable for IVF. Results: Diploid fertilization occurred in 52.6% o f cycles and 16.0% of oocytes (n = 263). The fertilization rate was in versely correlated to the proportion of spermatozoa coated with IgG in the Percoll-selected sperm suspension. Three of the 16 attempts in wh ich >90% of the spermatozoa were coated with IgG resulted in a low dip loid rate of 4.1%. Fertilization was obtained in 18 of the 22 attempts in which <90% of spermatozoa were IgG coated, with a diploid fertiliz ation rate of 22.8%. Association of both classes of antibodies (IgG an d IgA) further impaired the fertilization rate. Twenty ETs gave four p regnancies: one biochemical, one ongoing, and two giving birth to heal thy babies (1 singleton and 2 twins). Conclusions: Subzonal inseminati on is a potential solution for achieving fertilization in cases of IVF failure because of sperm autoimmunity. However, IgG inhibits in a dos e-dependent manner the fusion of gametes' membranes. Though the level of IgA antibodies does not appear as critical as that of IgG antibodie s, association of both classes of Igs impairs the probability of ferti lization.