Enhanced interleukin 1 generation by monocytes in vitro is temporally linked to an early event in the onset or exacerbation of rheumatoid arthritis.

Twenty-one patients with rheumatoid arthritis (RA) and 12 age and sex matched healthy controls were examined for the ability of their monocytes (adherent cells, AC) to spontaneously secrete interleukin 1 (IL-1) and for their peripheral blood mononuclear cells (PBMC) to secrete interleukin 2 (IL-2) induced by Staphylococcal Protein A (SPA). All RA patients had PBMC which secreted normal amounts of mitogen induced IL-2 regardless of disease activity or disease history. However, AC from RA patients who had a recent (less than 6 months) onset of their disease, or exacerbation of existing RA, had enhanced spontaneous IL-1 secretion. AC from patients with equally active RA but with historically stable disease generated normal amounts of IL-1. Enhanced in vitro IL-1 generation by circulating monocytes is temporally linked to an early event in the onset of exacerbation of RA.