REACTION OF AN ACTIVATED COMPLEX OF GUINEA-PIG COMPLEMENT COMPONENTS, C56, WITH UNSENSITIZED ERYTHROCYTES AND WITH ERYTHROCYTES CARRYING C3B MOLECULE

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 31  (1) , 151-158
Abstract
During the interaction of guinea pig complement [C] intermediate cells, EAC423 [erythrocyte, antibody plus C423 complex] with guinea pig C5 and C6, an activated complex of C5 and C6, .**GRAPHIC**. was demonstrated in the fluid phase of the reaction mixture, .**GRAPHIC**. also was eluted from EAC42356 which was generated by the interaction of EAC423 with C5 and C6. Both preparations of .**GRAPHIC**. showed quite similar characteristics and were not distinguished from one another. Both were capable of reacting with unsensitized E in the presence of C7 to form EC567. They were able to react with EAC43 in the absence of C7 to form EAC4356, but did not react with EAC43 pretreated with C3b inactivator, dithiothreitol or N-bromosuccinimide. Guinea pig .**GRAPHIC**. generated on EAC423 apparently has a tendency to dissociate into the fluid phase. The dissociated .**GRAPHIC**. can bind again to intact C3b molecule on the cells. The ability of cell-bound C3b to combine with .**GRAPHIC**. may lead to localization of .**GRAPHIC**. to the cell membrane carrying C3b, resulting in acceleration to attachment of .**GRAPHIC**. to the membrane. This assumption was supported since the replacement of E by EAC43 increased the susceptibility of the cells to lytic action of C induced by cobra venom factor. A new function of cell-bound C3b as localizing .**GRAPHIC**. to the membrane of sensitized cells was indicated.