Role of IgM-rheumatoid factor interference in the determination of total serum IgE and IgE-containing circulating immune complexes.
IgM-rheumatoid factor (RF) interference in the determination of total serum IgE and IgE-containing circulating immune complexes (IgE-CIC) was studied by inhibition experiments in vitro comparing a new ELISA technique free of IgM-RF interference with more widely used RIA methods. It was shown that a considerable overestimation of the IgE content in CIC can exist when high levels of IgM-RF are present in the same serum. The clinical part of this study revealed a dramatic fall in prevalence of IgE-CIC in patients with rheumatoid arthritis (RA) with the ELISA technique, compared with the more conventional RIA method (respectively 1/20 compared to 12/20 positive for IgE-CIC). In these patients, there was a good correlation between the level of IgM-RF and the amount of IgE detected in the CIC by the RIA method (r = 0.87) whereas the RF-interference free ELISA method showed no correlation between these two parameters (r = 0.06). Total serum IgE determination with a solid phase RIA was also influenced by IgM-RF interference, whereas the PRIST method was not affected by the presence of IgM-RF. In conclusion, in patients with rheumatic diseases, IgE-assays using polyclonal rabbit or sheep anti-IgE antibodies are not appropriate and monoclonal anti-IgE antibodies that have been proved not to interfere with IgM-RF should be advocated.
De Clerck
L S
LS
Laboratory of Immunology, University of Antwerp, Belgium.
Gigase
P L
PL
Bridts
C H
CH
Stevens
W J
WJ
D000936:Antigen-Antibody Complex / Q000032:analysis*; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001667:Binding, Competitive; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis*; D007075:Immunoglobulin M / Q000276:immunology*; D011863:Radioimmunoassay; D012217:Rheumatoid Factor / Q000276:immunology*
D000936:Antigen-Antibody Complex; D007075:Immunoglobulin M; D007073:Immunoglobulin E; D012217:Rheumatoid Factor