Changes in the inhibition of specific agglutination by plasma due to microvesicles released from human red cells during storage for transfusion.

The progressive appearance of erythrocyte antigenic activity in plasma from donations of human blood taken into acid citrate-dextrose (ACD) and stored at 4 degrees D for transfusion has been studied. It has been shown by specific inhibition tests that A, B, H and P1 activities are associated with membrane-bounded microvesicles which are released from the red cell membrane during the disc-echinocyte-spherocyte shape transformation. Although M group activity appears to be lost from the red cell membrane during storage, significant recovery on the microvesicles is not obtained even though these seem to contain the M and N group intrinsic protein, glycophorin.