Biomaterial Database

Mechanism of activation of the classical pathway of complement by monoclonal IgE (DES). Restricted regulation of C4b by C4b-binding protein. 1984

J M Saint-Remy

A human monoclonal IgE from patient DES, IgE (DES), has been shown to activate the classical pathway of complement. The mechanism of this activation has been investigated and can be summarized as follows: (a) IgE (DES) is able to bind and activate C1 in a dose-dependent fashion. This activation increases with the size of the aggregates used, but the affinity of C1 for IgE (DES) is weaker than for IgG. (b) A classical pathway C3 convertase can be assembled on IgE (DES) using purified C1, C4 and C2. The formation decay of this convertase is similar to that formed on IgG with an half-life of 9 min at 37 degrees C. (c) The extrinsic regulation of the C3 convertase by C4bp is restricted on IgE (DES) as compared to IgG. This restriction is shown on both the formation and the decay of the convertase. The mechanism of activation of the classical pathway of complement by IgE (DES) thus present some similarities with the assembly of the C3 convertase by the alternative pathway.

UI	MeSH Term	Description	Entries
D007073	Immunoglobulin E	An immunoglobulin associated with MAST CELLS. Overexpression has been associated with allergic hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).	IgE
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
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
D003171	Complement Pathway, Classical	Complement activation initiated by the binding of COMPLEMENT C1 to ANTIGEN-ANTIBODY COMPLEXES at the COMPLEMENT C1Q subunit. This leads to the sequential activation of COMPLEMENT C1R and COMPLEMENT C1S subunits. Activated C1s cleaves COMPLEMENT C4 and COMPLEMENT C2 forming the membrane-bound classical C3 CONVERTASE (C4B2A) and the subsequent C5 CONVERTASE (C4B2A3B) leading to cleavage of COMPLEMENT C5 and the assembly of COMPLEMENT MEMBRANE ATTACK COMPLEX.	Classical Complement Pathway,Classical Complement Activation Pathway,Complement Activation Pathway, Classical
D003172	Complement C1	The first complement component to act in the activation of CLASSICAL COMPLEMENT PATHWAY. It is a calcium-dependent trimolecular complex made up of three subcomponents: COMPLEMENT C1Q; COMPLEMENT C1R; and COMPLEMENT C1S at 1:2:2 ratios. When the intact C1 binds to at least two antibodies (involving C1q), C1r and C1s are sequentially activated, leading to subsequent steps in the cascade of COMPLEMENT ACTIVATION.	C1 Complement,Complement 1,Complement Component 1,C1, Complement,Complement, C1,Component 1, Complement
D003180	Complement C3b Inactivator Proteins	Endogenous proteins that inhibit or inactivate COMPLEMENT C3B. They include COMPLEMENT FACTOR H and COMPLEMENT FACTOR I (C3b/C4b inactivator). They cleave or promote the cleavage of C3b into inactive fragments, and thus are important in the down-regulation of COMPLEMENT ACTIVATION and its cytolytic sequence.	C3b Inactivators,C3b Inhibitors,Complement 3b Inactivators,Complement 3b Inhibitors,Complement C3b Inactivators,Complement C3b Inhibitor Proteins,Conglutinogen Activating Factors,Factors, Conglutinogen Activating,Inactivators, C3b,Inactivators, Complement 3b,Inactivators, Complement C3b,Inhibitors, C3b,Inhibitors, Complement 3b
D003181	Complement C4	A glycoprotein that is important in the activation of CLASSICAL COMPLEMENT PATHWAY. C4 is cleaved by the activated COMPLEMENT C1S into COMPLEMENT C4A and COMPLEMENT C4B.	C4 Complement,C4 Complement Component,Complement 4,Complement C4, Precursor,Complement Component 4,Pro-C4,Pro-complement 4,C4, Complement,Complement Component, C4,Complement, C4,Component 4, Complement,Component, C4 Complement,Pro C4,Pro complement 4
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000911	Antibodies, Monoclonal	Antibodies produced by a single clone of cells.	Monoclonal Antibodies,Monoclonal Antibody,Antibody, Monoclonal