Interleukin abnormalities in recently active rheumatoid arthritis.

Peripheral blood lymphocytes (PBL) from 14 patients with rheumatoid arthritis (RA) produced increased amounts of interleukin (IL) (p less than 0.05) as measured in a mouse thymocyte assay and showed enhanced proliferation in response to an IL containing supernatant (p less than 0.05) when compared with 9 age matched controls. Both enhanced IL production (p greater than 0.01) and responsiveness (p less than 0.002) were seen exclusively in a subgroup of 7 patients with a recent onset or exacerbation of their disease. PBL from RA patients with equally active disease which had been unchanged for more than 6 months produced and responded to IL normally. There was a direct correlation between IL production and responsiveness (r = 0.69, p less than 0.005). These 2 distinct IL abnormalities appear to reflect disease initiating or exacerbating factors in RA.