The Relationship Between Antibody Affinity and the Efficiency of Complement Fixation

Abstract

Abstract The efficiency of complement fixation by antigen-antibody complexes is shown for the first time to be directly related to the affinity of IgG antibody for its antigenic determinant. Decreased complement fixation by IgG antibody at 37°C is independent of antibody affinity. The biologic activity of the complexes in terms of complement fixation parallels their activity in the passive cutaneous anaphylaxis reaction. The implications of these observations with respect to the mechanisms of complement fixation by immune complexes formed with IgG antibody are discussed.