Rho (D) antigen content of human spermatozoa.

I-labelled anti-Rh (D) antibody was made to react with suspensions of spermatozoa and red blood cells from Rh (D) positive and negative donors at 37° for 1 hour. Spermatozoa from Rh (D) positive donors did not take up more I anti-Rh (D) than was bound by spermatozoa from Rh (D) negative donors. The mean value for Rh (D) positive donors was 0.0142±0.0061×10 μg. nitrogen per 10 spermatozoa, and the comparable value for Rh (D) negative donors was 0.0189±0.0130×10 μg. nitrogen per 10 spermatozoa. Red blood cells from Rh (D) positive donors took up thirty to forty times more I anti-Rh (D) antibody than was taken up by spermatozoa from Rh (D) positive donors, whereas red blood cells from Rh (D) negative donors took up only 0.5 to 1.7 times more I anti-Rh (D) antibody than was taken up by spermatozoa from Rh (D) negative donors. Pre-treatment of spermatozoa with trypsin increased by two to three times the quantity of I anti-Rh (D) antibody bound to spermatozoa from both Rh (D) positive and negative donors. The quantitative increase was similar for spermatozoa from Rh (D) positive and negative donors. No evidence for the presence of Rh (D) antigen on human spermatozoa was obtained using I anti-Rh (D).