Human agglutinins to rabbit erythrocytes. Characterization of an antigen

Crude preparations inhibiting the agglutination of rabbit erythrocytes by pooled human serum were obtained by extraction of erythrocyte stromata with various solvents (chloroform/methanol, trichloroacetic acid, and so forth). Highest inhibiting activity was found in a preparation containing sphingoglycolipid; 0.8 mug inhibited 2 agglutinating units of serum. The active preparations retained their activity after 5 min of incubation in a boiling water bath and after treatment with proteolytic enzymes or neuraminidase. Treatment with periodate abolished the activity. The antigenic site is therefore probably determined by the sugars of the sphingoglycolipid.