The antigens 4a and 4b in rhesus monkeys and stumptailed macaques

Small panels of rhesus and stumptailed macaques were tested in a cytotoxic assay against human and chimpanzee 4a and 4b alloantisera. The human antisera were also absorbed by macaque platelets and the effect on the serum titer against human cells considered. Results of both types of testing conclusively demonstrated the presence of 4a- and 4b-like antigens on the cells of these two macaque species. Although the frequencies of both specificities were different from those observed for man and chimpanzee, they showed an alternative distribution in the monkey populations as they do in the highest primates.