Cachectin/tumour necrosis factor-alpha in the circulation of patients with rheumatic disease.

By means of a sensitive double-antibody radioimmunoassay, cachectin/tumour necrosis factor-alpha (TNF) was measured in sera from 51 patients with rheumatic disease. Elevated levels of circulating cachectin/TNF were observed in 46% of patients with rheumatoid arthritis (RA; p less than 0.001 versus blood donors) and in 29% of patients with systemic lupus erythematosus (SLE; p less than 0.05 versus blood donors). Marked elevation of cachectin/TNF occurred in both RA and SLE patients in connection with severe infections. The results show that cachectin/TNF is present in the circulation of certain patients with rheumatic disease, and that although the median cachectin TNF level in SLE patients is lower than that in RA patients, the cachectin/TNF response in SLE patients to severe infections is similar to that in RA patients.