Quantitation of IgM, IgA and IgG rheumatoid factors by ELISA in rheumatoid arthritis and other rheumatic disorders.
We describe the evaluation of an enzyme-linked immunosorbent-assay (ELISA) for the measurement of IgM, IgA and IgG rheumatoid factor (RF). Results were obtained from sera of normal controls and patients with different rheumatic disorders in a cross-sectional study. Both human and rabbit IgG could be used as antigen in the assays. IgA-RF and IgG-RF were measured after pepsin digestion. The WHO reference preparation was used to standardise IgM-RF, but could not be used in the IgA- and IgG-RF assay, because neither IgA- nor IgG-RF could be detected in this standard serum. The ELISA for detection of RF is a highly sensitive and reproducible method and quantitation of results can be standardised. It yields good discriminative values for RA versus controls, in particular when more RF-isotypes are determined. In RA patients a correlation between IgM-, IgA- and IgG-RF concentrations does exist, although a wide variation was found in the ratio of these concentrations.
van Leeuwen
M A
MA
Department of Internal Medicine, University Hospital, Groningen, The Netherlands.
Westra
J
J
Limburg
P C
PC
de Jong
H J
HJ
Marrink
J
J
van Rijswijk
M H
MH
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D007075:Immunoglobulin M / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012216:Rheumatic Diseases / Q000097:blood*; D012217:Rheumatoid Factor / Q000032:analysis*; D012680:Sensitivity and Specificity
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012217:Rheumatoid Factor