| complement 5a, des-arginine | Complement 5a with the carboxy-terminal arginine removed. The arginine is rapidly cleaved from the c5a fragment during complement activation by carboxypeptidase b present in normal human serum. C5a des-arg shows complete loss of spasmogenic activity though it retains some chemotactic ability. (12 Dec 1998) |
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| complement 6 | The sixth component in the complement reaction sequence. It is a beta-globulin with a sedimentation coefficient of 8.7 and a molecular weight of 120,000 at 60 micrograms/ml in serum. It may exist in a complex with c5 and c7 and is activated by the binding of c5. (12 Dec 1998) |
| complement 7 | The seventh component in the complement reaction sequence. It is a beta-globulin probably in a complex with c5 and c6 and is activated by c5. The attachment of c7 renders the cell susceptible to lysis. (12 Dec 1998) |
| complement 8 | The next to the last essential component for cell lysis in the complement reaction sequence. It is a gamma-globulin with a molecular weight of 150,000 and a sedimentation coefficient of 8. It is present in trace amounts in serum and can be inhibited, like complement 1, by cation chelators. (12 Dec 1998) |
| complement 9 | The last component in the complement reaction sequence. It is an alpha-globulin present in serum as a trace, with a molecular weight of 80,000 and a sedimentation coefficient of 4.5. For cell lysis, it can be replaced by a metal chelator. (12 Dec 1998) |
| complement activating enzymes | <enzyme> Enzymes present in the complement system which activate one or more components in the system. Registry number: EC 3.- (12 Dec 1998) |
| complement activation | The sequential activation of serum components c1 through c9, initiated by an erythrocyte-antibody complex or by microbial polysaccharides and properdin, and producing an inflammatory response. (12 Dec 1998) |
| complement binding assay | A test for the detection of immune complexes. (05 Mar 2000) |
| complement cytolysis inhibitor | <protein> Vertebrate glycoprotein of uncertain function. Secreted as a 400 amino acid peptide, then cleaved to form two 200 amino acid peptides that are linked by a disulphide bridge. Synonym: complement associated protein, complement cytolysis inhibitor, glycoprotein III. (11 Jan 1998) |
| complement fixation | <immunology> Binding of complement as a result of its interaction with immune complexes (the classical pathway) or particular surfaces (alternative pathway). (18 Nov 1997) |
| complement-fixation reaction | <immunology> Binding of complement as a result of its interaction with immune complexes (the classical pathway) or particular surfaces (alternative pathway). (18 Nov 1997) |
| complement-fixation test | An immunological test for determining the presence of a particular antigen or antibody when one of the two is known to be present, based on the fact that complement is "fixed" in the presence of antigen and its specific antibody. See: Bordet-Gengou phenomenon. (05 Mar 2000) |
| complement fixation tests | Serologic tests based on inactivation of complement by the antigen-antibody complex (stage 1). Binding of free complement can be visualised by addition of a second antigen-antibody system such as red cells and appropriate red cell antibody (haemolysin) 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. (12 Dec 1998) |
| complement-fixing antibody | Antibody that combines with and sensitises antigen leading to the activation of complement, which may result in cell lysis. Synonym: CF antibody, sensitizing substance. (05 Mar 2000) |
| complement haemolytic activity assay | Usual screening assay for complement. Dilutions of the serum to be tested are added to antibody-coated erythrocytes and the percentage of lysis is measured. The values are expressed by ch50, haemolytic complement units per milliliter, which is the dilution of serum required to lyse 50 percent of the erythrocytes in the assay. (12 Dec 1998) |