Sheep Red Blood Cell Receptor and the Epitope Detected by Leu‐5 Monoclonal Antibody in Primates

The expression of the epitope detected by the monoclonal antibody Leu‐5 and the rosette formation with sheep red blood cells was examined for the mononuclear cells of 25 primate species including human subject. The plot of rosette‐forming cells against Leu‐5‐positive cells enabled us to classify these species into three large groups: hominoids–Old World monkeys (Leu‐5‐positive cells ≧ rosette‐forming cells), New World monkeys (Leu‐5‐positive cells < rosette‐forming cells), and prosimians (Leu‐5‐positive cells <5%, some of them with both Leu‐5‐positive cells and rosette‐forming cells <5%).