Human protamines and male infertility

Purpose: Our purpose was to determine the ratio of protamine 1 to protamine 2 in human spermatozoa and relate it to in vitro fertilization rates (IVF) and standard semen parameters. Methods: Couples who had been clinically diagnosed as having male-factor infertility and had undergone IVF treatment were grouped according to IVF rates and pregnancy outcome. Protamines were extracted and separated on acid urea polyacrylamide gels. The P1/P2 ratio correlation with semen parameters and IVF rates was investigated using nonparametric analysis. Results: The P1/P2 ratio ranged from 0.55 to 1.29 in the control group of patients, who had fertilization rates greater than or equal to 50% and had achieved a pregnancy in one IVF cycle. Of the test patients with IVF < 50%, three (14%) had P1/P2 ratios outside the range exhibited by the control group and their sperm possessed large heads. Conclusions: P1/P2 ratios were statistically negatively correlated with IVF rates in the control group and with progressive motile sperm concentration in the test group. We do not think that altered P1/P2 ratios are the primary cause of reduced fertilization.