Protease modification enhances anti-D binding to nucleated red blood cell precursors

Protease modification of nucleated red blood cell precursors resulted in significant enhancement of anti-D binding, indicating the presence of cryptic Rh determinants within the plasma membrane of the developing erythroid cell. Protease-modified nucleated precursor cells bound less anti-D than protease-modified mature red blood cells, however, suggesting that the total content of D antigen in the developing erythropoietic plasma membrane is reduced. These findings support the hypothesis that the D antigen, an integral membrane protein, is progressively synthesized during erythropoiesis.