High fertilization prediction by flow cytometric analysis of the CD46 antigen on the inner acrosomal membrane of spermatozoa.

The study was set up to determine the relationship between the human sperm acrosome reaction and fertilization in couples undergoing routine in-vitro fertilization (IVF) treatment. Prospective data analysis was carried out on all IVF patients during a 6 month period. Exceptions were those patients having insufficient sperm concentration to allow both acrosome reaction determination and insemination. The main outcome measures were the prediction of fertilization in IVF patients using flow cytometric analysis of the spontaneous and ionophore-induced acrosome reaction [giving the acrosomal response to ionophore challenge (ARIC) score] in the male partner's spermatozoa versus standard analytical methods of sperm motion parameters and morphology. Stepwise logistic regression indicated only two independent factors predictive of fertilization: ARIC score (chi 2 = 109.6, P < 0.0001) and post-Percoll % motility (chi 2 = 8.8, P < 0.003). Of patients with an ARIC score of > 10, 92% had > 30% of oocytes fertilized; 100% of patients with an ARIC score of < 10 had < 30% fertilization of oocytes. The sensitivity and specificity of the assay system were 1.00 and 0.82 respectively. The results would indicate that the ARIC test as measured by flow cytometric analysis of CD46 binding is a sensitive and specific assay for use in the prediction of fertilization in IVF patients, thus enabling direct channelling of those patients with ARIC scores of < 10 into the more invasive micro-assisted fertilization schemes.