Quantification of the C3d split products of human complement by a sensitive enzyme-linked immunosorbent assay.
A double-antibody biotin-avidin enzyme-linked immunosorbent assay (ELISA) for quantification of the C3d split products is described. Polyethylene glycol 6000 was used to precipitate large C3 molecules, and the C3d-containing supernatant was used in the assay. C3d was measured in ethylenediaminetetraacetic acid plasma from 40 healthy blood donors, and the normal range was defined. Twenty-two patients were tested, and 12 of these had increased levels of C3d. No correlation was observed between total C3 and C3d in these patients. There was a close correlation between C3d measured by this method and by the double-decker rocket immunoelectrophoresis method. The C3d ELISA method is very sensitive, easy to perform, and time-saving and economical compared with most C3d methods already described. A procedure to define the lower detection limit and examine the reliability of an ELISA method in general is discussed.
D000937:Antigen-Antibody Reactions; D003176:Complement C3 / Q000032:analysis* / Q000276:immunology / Q000592:standards; D015933:Complement C3d; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D006801:Humans; D007122:Immunoelectrophoresis; D007124:Immunoenzyme Techniques / Q000592:standards; D011092:Polyethylene Glycols; D011233:Precipitin Tests; D012015:Reference Standards; D012016:Reference Values
D003176:Complement C3; D011092:Polyethylene Glycols; D015933:Complement C3d