Avidin attachment to biotinylated erythrocytes induces homologous lysis via the alternative pathway of complement

Noncovalent attachment of avidin to the membrane of prebiotinylated red blood cells (RBCs) induces lysis via the alternative pathway of complement (APC). Lysis is not species-dependent; RBCs from humans, rabbits, rats, and sheep were lysed with both autologous and all heterologous sera. Both biotinylated and native cells were not lysed. Lysis was observed at an avidin surface density of about 10(5) molecules per cell. Acylation of avidin prevents lysis and decreases the positive charge of the avidin. Lysis depends on the length of the cross-linking agent used for the biotin attachment to the membrane. An increase in the length of the cross-linking agent was accompanied by an enhancement of the lysis and the agglutination titer of biotinylated RBCs in a solution of avidin. It is suggested that avidin attachment induces some transformations of the cell membrane that lead to the conversion from “APC nonactivator” cells to “APC activator” cells. The interaction of avidin with membrane APC-restrictors (decay-accelerating factors, type 1 receptor for complement, homologous restriction factor, and others), the charge of avidin, and its cross-linking ability in lysis are discussed. It is proposed that membrane rearrangement induced by multipoint avidin attachment to biotinylated membrane is the main reason for avidin-induced elimination of APC restriction.