Characterization and frequency distribution of sperm acrosome reaction among normal and infertile men.

We studied the acrosome reaction (AR) in human spermatozoa from 58 normal fertile men and 232 infertile patients. The median AR in the normal population was 17%; AR was > 9% in 83% of the subjects studied and only 2% of fertile individuals had a failed AR (< 5%). We calculated the within person variability using multiple specimens from each subject; the 95% confidence interval for each subject was 4 AR units above and 4 AR units below his mean value. In contrast, the median AR for the infertile population was 3%. AR values were below the normal range (< 5%) in 60% of the patients and only 26% of the patients had AR values > 9%. Because patients entered the study sequentially, without regard to the aetiology of infertility, the patient population comprised a wide variety of subjects ranging from individuals with good to extremely poor semen quality. There was a progressively greater number of individuals with a failed AR as semen quality deteriorated (P < 0.01). However, among patients with good count, motility and morphology, 20% unexpectedly had a failed AR, and among patients with severely impaired semen quality, 29% had a positive AR. We also analysed the relationship of AR values with other semen measurements. The frequency of acrosomal reactions was significantly correlated (Spearman, P < 0.001) with morphology (r = 0.509), concentration (r = 0.524), progression (r = 0.416) and percentage motility (r = 0.356), but not with the percentage of sperm moving at a curvilinear velocity of < or = 40 microns/s.(ABSTRACT TRUNCATED AT 250 WORDS)