Characterization of the T antigen and T agglutinin in inbred rats.

Treatment of rat erythrocytes with vibrio cholerae neuraminidase (VCN) exposed antigenic determinants on the cell surface membrane, and autologous rat serum contained antibodies which reacted with these determinants and with VCN-treated human erythrocytes. The antibodies were not present in sera of animals less than 8 weeks of age. Human serum also contained antibodies which reacted with the VCN-treated rat erythrocytes. Lectin isolated and purified from Arachis hypogoea agglutinated VCN-treated rat erythrocytes. This system has the characteristics of the T antigen which had been described initially in humans. Absorption studies showed that the VCN-treated rat erythrocyte membrane antigen cross-reacted with the VCN-treated human erythrocyte membrane antigen. Absorption of rat sera and the lectin solution with VCN-treated rat or human erythrocytes removed all of the molecules capable of reacting with both rat and human erythrocytes. Absorption of human sera with VCN-treated human cells removed their reactivity with both cell types, but absorption with VCN-treated rat cells did not remove completely their reactivity with VCN-treated human erythrocytes. These results indicate that the VCN-treated rat cells contain antigenic determinants which are identical to some on the VCN-treated human cells and that the human sera contain antibodies to additional antigenic specificities not shared with rat red blood cells. Haemagglutination inhibition studies with different sugars, T antigen from human erythrocyte membranes and desialylated glycoprotein from rat erythrocyte membranes showed that the T antigen, the desialylated glycoprotein and the sugars containing a terminal non-reducing beta-D-galactosyl residue inhibited the reactivity of the lectin, the rat sera and the human sera with both human and rat red blood cells. These findings show that the antigenic reactivity of the VCN-treated rat red blood cells residues in the membrane glycoproteins and that the immunodominant group is a carbohydrate. Thus, the rat has a T antigenic system very similar to that of the human.