The fixation of complement and the activated first component (C1) of complement by complexes formed between antibody and divalent hapten.
Hapten-antibody complexes prepared at equivalence with the bivalent hapten bis-DNP-octamethylene-diamine and purified rabbit anti-DNP antibody were fractionated by Sepharose gel-filtration and the fractions examined by electron microscopy. Individual fractions were tested for whole-complement fixation and C1 fixation. Dimer forms did not show this type of biological activity, while fractions containing tetramers and larger polymers exhibited both C and C1 fixation, which could be inhibited by prior exposure of the complexes to the univalent hapten epsilon-DNP-caproic acid. The dose-response result indicated that the C-fixation observed was not due to interpolymeric cooperative effects. It was concluded that in the generation of biological activity by soluble antigen-antibody complexes made with complement-fixing antibody, quaternary structural changes following specific combination with antigen may be as important as any tertiary structural alterations that occur in the individual immunoglobulin molecule.
D000818:Animals; D000906:Antibodies / Q000032:analysis; D000917:Antibody Formation; D001665:Binding Sites; D002021:Buffers; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003168:Complement Fixation Tests; D003165:Complement System Proteins / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D004140:Dinitrophenols; D006460:Hemolysin Proteins; D007118:Immunoassay; D008854:Microscopy, Electron; D011817:Rabbits; D014461:Ultracentrifugation
D000906:Antibodies; D002021:Buffers; D004140:Dinitrophenols; D006460:Hemolysin Proteins; D003165:Complement System Proteins