Inhibition of Erythroid Progenitor Cells by Anti-Kell Antibodies in Fetal Alloimmune Anemia

The Kell blood-group system is one of the major antigenic systems in human red cells. It consists of 23 known antigens that reside on one 93-kd transmembrane protein encoded by a single gene on chromosome 7 (7q33). 1 , 2 The Kell antigen is expressed only by erythroid progenitor cells and mature erythroid cells. 1 , 3 , 4 The Kell blood group is important in clinical medicine because antibodies to the principal antigen, K1, cause both life-threatening transfusion reactions and severe alloimmune anemia in Kell-positive fetuses and newborn infants. 5 , 6 Alloimmunization occurs when Kell-negative women, who do not have the K1 antigen on their . . .