Mechanisms of Increased Susceptibility to C Lysis of Abnormal Human Red Blood Cells

Abstract

Abstract The cells of patients with paroxysmal nocturnal hemoglobinuria (PNH) and hereditary erythroblastic multinuclearity with positive acidified serum test (HEMPAS) are abnormally susceptible to lysis by C and cold-reactive antibodies, but for different reasons. For PNH cells, the fixation of antibody, C1 and C4 is the same as for normal cells. However, the amount of C3 fixed/C4 is increased 3- to 7-fold. The amount of C3 fixed for a given degree of lysis is about one-third that of normal cells. In a less sensitive variant of PNH cells, the amount of C3 fixed/C4 was about the same as for the markedly abnormal cells, but the amount of C3 fixed for a given amount of lysis was the same as for normal cells. Normal cells treated with sulfhydryl-reactive agents resembled PNH cells in these reactions. HEMPAS cells fix 2 to 3 times as much of some, but not other, examples of anti-I. The amount of C1 fixed/Ab is normal.