title: A monoclonal antibody which can distinguish between the two isotypes of human C4.
abstract: A monoclonal antibody to Human C4 (L003) has been shown to bind to the polymorphic C4d fragment of the alpha-chain of C4. Another monoclonal antibody (L001) was shown to bind to the beta-chain. L003 reacts differently with the two isotypes of C4, C4-A and C4-B. The equilibrium constant of L003 for C4-B is approx. 7-fold higher than that for C4-A, while L001 has similar affinity for both C4 types. Also, L003 binding to C4-A is very much more pH dependent than is its binding to C4-B. These observations explain the very useful property of L003 in being able to separate the two isotypes by affinity chromatography.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000915:Antibody Affinity; D002846:Chromatography, Affinity; D003181:Complement C4 / Q000032:analysis* / Q000378:metabolism; D015935:Complement C4b; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010446:Peptide Fragments / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D003181:Complement C4; D010446:Peptide Fragments; C033860:complement C4c; D015935:Complement C4b; C032261:complement C4d