Differentiation between antibodies to protamines and somatic nuclear antigens by means of a comparative fluorescence study on swollen nuclei of spermatozoa and somatic cells.

The indirect immunofluorescence test on swollen nuclei of rat thymocytes, chicken red blood cells and human and salmon spermatozoa was found to be an easy and satisfactory method for the discrimination between antibodies to sperm-specific nuclear antigens and somatic nuclear antigens. This study shows that nuclear antibodies present in the sera of vasectomized men and in rabbit antisera to human protamines are directed against the human sperm-specific nuclear antigens (protamines), and that they may cross-react with salmon protamine. These sera do not react with somatic nuclear antigens. This comparative fluorescence study and a complement fixation study, performed with sera from diabetic patients, proved that the administration of insulin retard (protamine-zinc-insulin) may lead to the formation of antibodies to the fish protamine. These antibodies may reveal a weak cross reaction with human protamines. The results obtained in this study also prove that the nuclei of chicken red blood cells and human sperm do not contain, or contain very small amounts of, histone fraction H1, and that salmon sperm nuclei do not contain any of the histone fractions, and suggest that the nuclei of mature human spermatozoa contain smaller amounts of histones in comparison to somatic cell nuclei.