Complement activation by a univalent hapten-antibody complex.

The mechanism of activation of the first component of complement by a univalent hapten-IgG antibody complex.

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 co...

Activation of antibody Fc function by antigen-induced conformational changes.

IgM antibody directed against the pheny-beta-lactoside hapten was examined for its capacity to fix complement in the presence of the hapten, monohapten-substituted antigen, and multihapten-substituted antigen. Hapten was found to have no effect; monovalent antigen induced an excellent response which could be inhibited by hapten; and multivalent antigen also induced an excellent response which w...

Binding of Antigen by Immunocytes

The binding of antigen to cells with antibody on their surface has been studied in a model system consisting of murine myeloma cells (MOPC 315) and DNP conjugates. Specific binding occurred between the DNP groups of DNP conjugates and cell surface immunoglobulin. Using this model, the binding affinities of multivalent and univalent DNP conjugates were measured directly by equilibrium-binding te...

Serologic Studies of Proteolytic Fragments of Rabbit Agglutinating Antibodies.

The reaction of the bivalent rabbit antibody molecule with papain (1, 2) or pepsin (3) and a reducing agent results in the release of two univalent fragments. The evidence for univalence is provided by the capacity of the fragments of hydrolyzed antiprotein antibody to inhibit specifically the homologous precipitin reaction (2), and by direct measurements of the maximal number of moles of hapte...