Detection of complement components on unlysed erythrocytes from acid hemolysis and thrombin test reactions in paroxysmal nocturnal hemoglobinuria.

As a result of an unidentified red cell defect, erythrocytes from patients with paroxysmal nocturnal hemoglobinuria 1 are susceptible to hemolysis in acidified fresh serum (1). This acid hemolysis reaction is augmented by commercial bovine thrombin (2). The role of serum complement in these PNH hemolytic reactions has not been entirely clear (3). Previous studies from this laboratory, utilizing AH *PNHE and Thr PNHE, have demonstrated the presence of complement on the surface of these cells (4). The present studies provide a more detailed analysis of the components of complement found on AHL PNHE and Thr*PNHE and compare these findings with the components of complement found on residual, unlysed normal erythrocytes surviving