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Activation of the alternative complement pathway by the immune precipitate formed with F(ab')2 fragment of human IgG antibody. 1983

Y Akagaki, and S Inai

The complement fixing ability of the F(ab')2 fragment of human IgG was studied using an immune precipitate (Ippt) formed between tetanus toxoid and the F(ab')2 of high-titer IgG antibody against tetanus toxin. A major subclass of the specific IgG antibody against tetanus toxin, which was separated by affinity column chromatography, was identified as IgG1. On incubation of normal human serum (NHS) with the Ippt formed at equivalence, a dose-dependent consumption of CH50, C3 and C5 activities was observed without significant loss of the early acting complement components. A similar consumption of CH50, C3 and C5 activities was found in NHS reacted with Ippt formed at any antigen/antibody ratio. The Ippt formed at antibody excess was more efficient in complement consumption than the Ippt formed at antigen excess. An apparent consumption of C3 and C5 activities was also noted in C4-deficient guinea pig serum treated with Ippt. When Ippt was incubated with Mg2+--EGTA-treated NHS, both C3 and C5 convertases of the alternative pathway were generated on the Ippt. From these results, it was concluded the the F(ab')2 of human IgG antibody, especially IgG1 antibody, when it formed an Ippt with antigen, could activate the alternative complement pathway.

UI MeSH Term Description Entries
D007074 Immunoglobulin G The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B. Gamma Globulin, 7S,IgG,IgG Antibody,Allerglobuline,IgG(T),IgG1,IgG2,IgG2A,IgG2B,IgG3,IgG4,Immunoglobulin GT,Polyglobin,7S Gamma Globulin,Antibody, IgG,GT, Immunoglobulin
D007140 Immunoglobulin Fab Fragments Univalent antigen-binding fragments composed of one entire IMMUNOGLOBULIN LIGHT CHAIN and the amino terminal end of one of the IMMUNOGLOBULIN HEAVY CHAINS from the hinge region, linked to each other by disulfide bonds. Fab contains the IMMUNOGLOBULIN VARIABLE REGIONS, which are part of the antigen-binding site, and the first IMMUNOGLOBULIN CONSTANT REGIONS. This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN. Fab Fragment,Fab Fragments,Ig Fab Fragments,Immunoglobulins, Fab Fragment,Fab Immunoglobulin Fragments,Immunoglobulin Fab Fragment,Immunoglobulins, Fab,Fab Fragment Immunoglobulins,Fab Fragment, Immunoglobulin,Fab Fragments, Immunoglobulin,Fragment Immunoglobulins, Fab,Fragment, Fab,Immunoglobulin Fragments, Fab
D003166 Complement Activating Enzymes Enzymes that activate one or more COMPLEMENT PROTEINS in the complement system leading to the formation of the COMPLEMENT MEMBRANE ATTACK COMPLEX, an important response in host defense. They are enzymes in the various COMPLEMENT ACTIVATION pathways. Activating Enzymes, Complement,Enzymes, Complement Activating
D003167 Complement Activation The sequential activation of serum COMPLEMENT PROTEINS to create the COMPLEMENT MEMBRANE ATTACK COMPLEX. Factors initiating complement activation include ANTIGEN-ANTIBODY COMPLEXES, microbial ANTIGENS, or cell surface POLYSACCHARIDES. Activation, Complement,Activations, Complement,Complement Activations
D003168 Complement Fixation Tests Serologic tests based on inactivation of complement by the antigen-antibody complex (stage 1). Binding of free complement can be visualized by addition of a second antigen-antibody system such as red cells and appropriate red cell antibody (hemolysin) requiring complement for its completion (stage 2). Failure of the red cells to lyse indicates that a specific antigen-antibody reaction has taken place in stage 1. If red cells lyse, free complement is present indicating no antigen-antibody reaction occurred in stage 1. Complement Absorption Test, Conglutinating,Conglutination Reaction,Conglutinating Complement Absorption Test,Complement Fixation Test,Conglutination Reactions,Fixation Test, Complement,Fixation Tests, Complement,Reaction, Conglutination,Reactions, Conglutination,Test, Complement Fixation,Tests, Complement Fixation
D003170 Complement Pathway, Alternative Complement activation initiated by the interaction of microbial ANTIGENS with COMPLEMENT C3B. When COMPLEMENT FACTOR B binds to the membrane-bound C3b, COMPLEMENT FACTOR D cleaves it to form alternative C3 CONVERTASE (C3BBB) which, stabilized by COMPLEMENT FACTOR P, is able to cleave multiple COMPLEMENT C3 to form alternative C5 CONVERTASE (C3BBB3B) leading to cleavage of COMPLEMENT C5 and the assembly of COMPLEMENT MEMBRANE ATTACK COMPLEX. Alternative Complement Pathway,Properdin Pathway,Alternative Complement Activation Pathway,Complement Activation Pathway, Alternative
D004306 Dose-Response Relationship, Immunologic A specific immune response elicited by a specific dose of an immunologically active substance or cell in an organism, tissue, or cell. Immunologic Dose-Response Relationship,Relationship, Immunologic Dose-Response,Dose Response Relationship, Immunologic,Dose-Response Relationships, Immunologic,Immunologic Dose Response Relationship,Immunologic Dose-Response Relationships,Relationship, Immunologic Dose Response,Relationships, Immunologic Dose-Response
D005779 Immunodiffusion Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction. Gel Diffusion Tests,Diffusion Test, Gel,Diffusion Tests, Gel,Gel Diffusion Test,Immunodiffusions,Test, Gel Diffusion,Tests, Gel Diffusion
D006461 Hemolysis The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity. Haemolysis,Extravascular Hemolysis,Intravascular Hemolysis,Extravascular Hemolyses,Haemolyses,Hemolyses, Extravascular,Hemolyses, Intravascular,Hemolysis, Extravascular,Hemolysis, Intravascular,Intravascular Hemolyses
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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