title: Pokeweed mitogen-induced secretion of IgG- and IgM-rheumatoid factors by synovial fluid and blood B lymphocytes in rheumatoid arthritis.
abstract: Lymphocytes from patients with rheumatoid arthritis (RA) were assayed for their ability to secrete Ig and rheumatoid factors (RF) upon polyclonal activation in vitro. B lymphocytes secreting IgM-RF and IgG-RF were enumerated using hemolytic plaque forming cell (PFC) assays. The sensitivity of RF-PFC formation was similar to that of a reverse PFC assay detecting all cells secreting Ig. Blood mononuclear cells from RA patients generated a median of 12 IgM-RF and 15 IgG-RF-secreting cells/10(6) after 6 days culture with pokeweed mitogen (PWM). Thus a median of approximately 0.5% of IgM- and IgG-secreting cells were identified as RF-PFC. Synovial fluid B lymphocytes co-cultured with autologous blood T lymphocytes in the presence of PWM generated higher numbers of RF-secreting cells; medians of 43 IgM-RF and 441 IgG-RF secreting cells/10(6) were found. Thus, 8-9% of IgM- and IgG-secreting cells from synovial fluid were identified as RF-PFC. In co-cultures containing synovial fluid T cells, PWM-induced RF secretion was low. The data indicate that both blood and SF B cells have the potential for RF secretion.
mesh_terms: D000917:Antibody Formation; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism*; D011043:Pokeweed Mitogens; D012217:Rheumatoid Factor / Q000378:metabolism*; D013582:Synovial Fluid / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011043:Pokeweed Mitogens; D012217:Rheumatoid Factor