Determination of C4b.C4-bp complex formed by the activation of classical complement pathway using an enzyme-linked immunosorbent assay.
We developed a quantitative enzyme-linked immunosorbent assay (ELISA) for the detection of C4b.C4-bp complex by incubating the sample on anti-C4-bp-coated plate and then developing with HRP-labeled anti-C4. The amount of C4b.C4-bp complex, generated in vivo by the interaction of purified C4b with C4-bp or normal human serum with aggregated human IgG, was measured by the ELISA. The complex, however, rapidly decreased in serum by the action of factor I. Six out of the 100 plasma samples from patients with various diseases were found positive in the ELISA. One plasma sample from a patient with SLE showed high level of C4b.C4-bp complex with decreased levels of factor I, C4, C4-bp and CH50. These results suggest that the detection of C4b.C4-bp complex is useful for monitoring the diseases in which the classical pathway activation is expected.
D001172:Arthritis, Rheumatoid / Q000276:immunology; D002352:Carrier Proteins / Q000032:analysis*; D003167:Complement Activation; D003181:Complement C4 / Q000032:analysis*; D015935:Complement C4b; D003169:Complement Inactivator Proteins; D003171:Complement Pathway, Classical; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005921:Glomerulonephritis / Q000276:immunology; D005922:Glomerulonephritis, IGA / Q000276:immunology; D006023:Glycoproteins; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D046911:Macromolecular Substances; D012859:Sjogren's Syndrome / Q000276:immunology
D002352:Carrier Proteins; D003181:Complement C4; D003169:Complement Inactivator Proteins; D006023:Glycoproteins; D046911:Macromolecular Substances; D015935:Complement C4b