Homologous species restriction in lysis of erythrocytes by terminal complement proteins.

Abstract

The cytolytic efficiency of the terminal complement protein complex, C5b-9, varies with the species of origin of C8 and C9. The susceptibility of erythrocytes [E] from various species to lysis by C5b6, 7 plus C8 and C9 from different species was studied. EC5b6, 7 intermediates were prepared on human, guinea pig, rabbit, mouse and rat E with human C5b6 and guinea pig C7. The degree of lysis of these intermediates by C8 and C9 varied widely depending on the species of the proteins and the target cells. In all cases, lysis was least efficient when C8 and C9 were homologous with respect to the target cell species. This effect was mostly attributable to C9. The inefficient lysis in a homologous system is not due to a failure to C9 binding. Rather, the poor lysis in the homologous system may be attributable to inefficient membrane insertion or channel formation.