COMPLEMENT SENSITIVITY OF PAROXYSMAL-NOCTURNAL HEMOGLOBINURIA BONE-MARROW CELLS

Abstract

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder in which erythrocytes [RBC], granulocytes and platelets are defective, as shown by increased susceptibility of RBC, WBC [white blood cells] and platelets to complement-mediated lysis in vitro. The sensitivity of PNH and non-PNH erythroid and myeloid precursors to complement lysis was studied using the release of 59Fe and myeloperoxidase as specific markers to monitor the lytic action of complement on erythroid and myeloid cell precursors, respectively. Erythroid cell precursors in 4 of 4 PNH patients demonstrated increased sensitivity to complement-mediated lysis. Myeloid cell precursors in 4 of 5 PNH patients exhibited increased sensitivity to complement and antibody. CFU-c [granulocytic progenitor cells] growth was below normal in the marrow of 7 PNH patients. The defect in PNH apparently occurs at the level of the hematopoietic stem cell.