SOLID-PHASE ENZYME IMMUNOASSAY OR RADIOIMMUNOASSAY FOR DETECTION OF IMMUNE-COMPLEXES BASED ON THEIR RECOGNITION BY CONGLUTININ - CONGLUTININ-BINDING TEST - COMPARATIVE-STUDY WITH I-125-LABELED CLQ BINDING AND RAJI-CELL RIA TESTS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 29  (2) , 342-354
Abstract
Bovine conglutinin was used in a solid-phase assay for the detection of immune complexes. In a 1st step, the tested serum sample is incubated in polypropylene tubes coated with conglutinin to allow C3[complement component 3]-coated immune complexes to bind to solid-phase conglutinin. In a 2nd step, the conglutinin-bound complexes are detected using an enzyme-conjugated or radiolabeled anti-immunoglobulin [Ig] antibody. The conglutinin-binding (KgB) test does not suffer from the interference of DNA, heparin or endotoxins. Its limit of sensitivity for aggregated IgG is 3 .mu.g/ml undiluted human serum. Immune complexes prepared in vitro using tetanus toxoid or DNA, and corresponding antibodies in human sera could be detected at various antigen/antibody ratios and at antibody concentrations lower than 8 .mu.g/ml. The KgB test allowed for the detection of immune complexes in sera from patients with systemic lupus erythematosus, rheumatoid arthritis, idiopathic vasculitis, leprosy and leukemia. These sera were also tested using the 125I-labeled C1q-binding activity (BA) test and the KgB test simultaneously, and a significant rank order correlation was observed. In patients with leukemia, a significant correlation was observed using 3 tests, KgB, 125I-labeled C1q BA and [human Burkitt''s lymphoma] Raji cell radioimmunoassay (RIA). KgB test appears as a simple and reproducible method, utilizing a very stable reagent, with a sensitivity and specificity comparable to the other tests studied and allowing for clinical application.