title: Hidden 19S IgM rheumatoid factor in synovial fluid.
abstract: Synovial fluid (SF) of 16 adult patients with rheumatoid arthritis (RA) and 9 children with juvenile rheumatoid arthritis (JRA) was investigated for the presence of hidden 19S IgM rheumatoid factor (RF). SF was incubated with 500 IU hyaluronidase/g of SF, dialyzed against acetate buffers at decreasing pH, centrifuged and subjected to chromatography on a Sephadex G-200 column. The resulting IgM-containing fraction of SF from 5 seropositive patients (3 adult RA, 2 JRA patients) demonstrated RF activity by the complement-dependent hemolytic assay. Hidden 19S IgM RF was not found in the IgM-containing fractions of SF from 13 adult seronegative RA patients. Hidden 19S IgM RF was shown in the IgM-containing fraction of SF in 4 of 7 children with seronegative JRA.
mesh_terms: D000328:Adult; D001171:Arthritis, Juvenile / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000276:immunology; D005591:Chemical Fractionation; D002648:Child; D002675:Child, Preschool; D003956:Dialysis / Q000379:methods; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007075:Immunoglobulin M / Q000302:isolation & purification*; D012217:Rheumatoid Factor / Q000032:analysis*; D013582:Synovial Fluid / Q000276:immunology* / Q000502:physiology
chemical_list: D007075:Immunoglobulin M; D012217:Rheumatoid Factor