Lattice Formation in Complement Fixation: Studies with Univalent Rabbit Antibody

Abstract

Hybrid univalent 6.5S antibody molecules, formed by recombination of half-molecules of rabbit antibody to ovalbumin with those of normal rabbit γ_G-globulin, fail to fix complement in reactions with homologous antigen. Such hybrid molecules, however, block complement fixation by intact antibody to ovalbumin. Molecules of antibody reconstituted in the absence of other protein retain the capacity to fix complement. The data suggest that small complexes containing excess univalent antibody do not fix complement and that lattice formation is required for fixation.