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.