Nonspecific Binding of Complement by Digestion Fragments from Antiviral Gamma Globulin.

The nonspecificity of rabbit gamma-globulin (antibody) to western equine encephalitis virus and the non-specificity of normal rabbit gamma-globulin in complement-fixation tests with anti-gens prepared from chick-embryo cells infected with this virus and normal chick-embryo cells resided primarily in Porter's fragment III. Addition of complement to fragment III from the anti-body globulin, followed by inactivation of the added complement, abolished the complement-fixing ability of fragment III with both specific and nonspecific antigens. Similar treatment of the undigested antibody abolished its complement-fixing ability with nonspecific antigen only.