Molecular Analysis of the Reaction of C9 with EAC1-8: Reaction of C9 with EAC1-8

Abstract

The hemolytic dose-response curve of either C9gp or C9hu using EAC1-8gp was shown to be concave to the abscissa representing the concentration of C9, but that of either C9gp or C9hu using EAC1-8hu was sigmoidal. When the number of molecules of C9 bound to EAC1-8 was calculated by subtracting the number of residual C9 molecules, which was not bound to the cells after reaction with EAC1-8, from that of added C9, it was found that one molecule of C9 bound to EAC1-8gp could generate about one site, but four or more molecules of bound C9 per cell might be necessary to generate one site on EAC1-8hu. Kinetic studies using EAC1-8hu and C9gp revealed that the generation of E* and lysis of E* proceeded with lag phase and the maximal velocities of these reactions were not proportional to the concentration of C9gp and EAC1-8hu. It was concluded from these results that EAC1-8gp could be lysed by one molecule of either C9gp or C9hu, and that more than one molecule of C9gp or C9hu might be necessary to produce a membrane lesion responsible for the hemolysis of EAC1-8hu.