A human antiserum reacting with modified blood group M determinants.

In the serum of a healthy blood donor, Mar, antibodies were identified that agglutinate blood group M erythrocytes only after their preincubation in glucose-containing solution. This agglutination was inhibited by blood group M glycoprotein preincubated in glucose solution but not by untreated M and N glycoproteins or N glycoprotein pretreated with glucose. A similar "activating' effect on M erythrocytes or M glycoprotein was achieved when glucose was replaced by mannose or N-acetylglucosamine, whereas several other replaced by mannose or N-acetylglucosamine, whereas several other sugars were ineffective. The "activating' effect of glucose on M antigen was time-, temperature-, pH-, and concentration-dependent. The binding of glucose to M glycoprotein was demonstrated under the preincubation conditions used in the above mentioned agglutinations. The results obtained suggest that the antibodies of serum, Mar, react with blood group M determinants modified by formation of a glycosylamine linkage between amino groups of the glycoprotein and glucose or other hexoses with the same configuration at asymmetric carbons 3, 4 and 5 as glucose.