title: IgM rheumatoid factor elaboration by blood, bone marrow, and synovial mononuclear cells in patients with rheumatoid arthritis.
abstract: IgM rheumatoid factor (RF) elaboration by rheumatoid arthritis (RA) synovial, bone marrow, and blood mononuclear cells (MNC) is reported. IgM RF was prepared from RF-positive sera by sequential euglobulin precipitation, Sephacryl S300 gel filtration, and IgG-Sepharose affinity chromatography. Purified material, which contained no detectable IgG or IgA, was used in an enzyme-linked immunosorbent assay (ELISA) to quantitate cellular elaboration of IgM RF. Excellent standard curves (r2 = 0.98) were obtained without nonspecific binding of samples or antisera to IgG-coated microtiter plates and without cross-reactivity of standards with antisera other than anti-IgM. We found RA blood MNC (11 patients) spontaneously averaged 15 ng/ml IgM RF (6% of total IgM produced), but elaborated 254 ng/ml IgM RF following pokeweed mitogen (PWM) stimulation (22 patients), exceeding that of 13 normal controls. Bone marrow MNC spontaneously (4 patients) produced 71 ng/ml IgM RF and secreted 78 ng/ml IgM RF with PWM stimulation (9 patients). In contrast synovial fluid MNC (5 patients) spontaneously elaborated 6652 ng/ml IgM RF, significantly (P less than 0.05) more than blood or bone marrow MNC; PWM-stimulated synovial fluid MNC (5 patients) produced 5472 ng/ml IgM RF. These observations confirm selective localization of activated, IgM RF-producing cells to the rheumatoid synovial space.
mesh_terms: D000921:Antibody-Producing Cells / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001402:B-Lymphocytes / Q000378:metabolism; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000096:biosynthesis*; D008297:Male; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000096:biosynthesis*; D013582:Synovial Fluid / Q000166:cytology*
chemical_list: D007075:Immunoglobulin M; D012217:Rheumatoid Factor