Species-specific glycoproteins of the human red cell membrane

Specific antiserum of human red cells was prepared from rabbit anti-human red cell serum by absorption with red cells of horse, hog, dog and Japanese monkey. This antiserum proved specific for human red cells regardless of blood types ABO and MN as demonstrated by the hemagglutination test. Sialoglycoproteins were extracted with lithium diiodosalicylate and isolated through chromatographic procedures from human red cell membranes, and showed inhibitory activity for the specific antiserum as well as for anti-M and anti-N sera. The isolated glycoproteins corresponded to the sialoglycoproteins on the basis of SDS-PAG electrophoresis. The inhibitory activity of the sialoglycoproteins for the specific antiserum was lost after the substance was treated with sialidase for 24h. A moderate reduction of the inhibitory activity for anti-M and anti-N sera but not for the specific antiserum was seen after treatment for 1h. These results showed that the receptors for the species-specific antiserum were more resistant towards sialidase treatment.