Raji cell assay for immune complexes. Evidence for detection of Raji-directed immunoglobulin G antibody in sera from patients with systemic lupus erythematosus.
Open Access
- 1 August 1980
- journal article
- Published by American Society for Clinical Investigation in JCI Insight
- Vol. 66 (2), 353-360
- https://doi.org/10.1172/jci109863
Abstract
We asked whether binding of human immunoglobulin (Ig)G antibody reacting with Raji cells could be distinguished from binding of IgG immune complexes. Using a standard Raji assay employing 125I-IgG goat anti-human Fc gamma, we found that digestion of Raji cells with pronase reduced by 95% their ability to bind complement-fixed aggregated human gamma globulin and complement-fixed tetanus toxoid-antitetanus toxin complexes. However, binding at 37 degrees C of IgG from the sera of 16 patients with systemic lupus erythematosus (SLE) to pronase-digested Raji cells was reduced much less consistently and extensively (9-100% reduction; mean reduction of 51%). In more detailed studies of two SLE sera, sucrose density gradient centrifugation showed that greater than 50% of the IgG binding to undigested Raji cells sedimented in the 7S region. Pepsin digestion of immunoglobulin fractions from four SLE sera caused a reduction in SLE IgG binding to undigested Raji cells when detected with 125I anti-Fc gamma, but an increase when binding was detected with 125I-anti-Fab, suggesting that substantial SLE IgG can bind through F(ab')2 regions. Binding of IgG from SLE sera was not directed at neoantigenic sites induced by pronase digestion because binding activity was adsorbed with undigested cells as readily as with digested cells. Moreover, sera from 10 SLE patients that had negative Raji assays contained no IgG that bound to pronase-digested Raji cells. We conclude that much of the IgG bound at 37 degrees C to Raji cells from the sera of many patients with SLE does not represent immune complexes but is probably antibody directed toward sites on the Raji cell.Keywords
This publication has 17 references indexed in Scilit:
- Antibody-dependent cell-mediated cytotoxicity in selected autoimmune diseases.JCI Insight, 1976
- Serum and synovial fluid inhibitors of antibody‐mediated lymphocytotoxicity in rheumatoid arthritis and systemic lupus erythematosusArthritis & Rheumatism, 1976
- The Raji cell radioimmune assay for detecting immune complexes in human sera.JCI Insight, 1976
- Nature of cold‐reactive antibodies to lymphocyte surface determinants in systemic lupus erythematosusArthritis & Rheumatism, 1975
- BINDING OF SOLUBLE IMMUNE COMPLEXES TO HUMAN LYMPHOBLASTOID CELLSThe Journal of Experimental Medicine, 1974
- ANTIBODIES TO A SPECIFIC SURFACE ANTIGEN OF T CELLS IN HUMAN SERA INHIBITING MIXED LEUKOCYTE CULTURE REACTIONSThe Journal of Experimental Medicine, 1973
- Studies of human sera with cytotoxic activityJCI Insight, 1971
- Cytotoxins in DiseaseNew England Journal of Medicine, 1970
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970
- General methods for the study of cells and serum during the immune response: the response to dinitrophenyl in mice.1969