Circulating human leucocyte elastase in rheumatoid arthritis.

Elastase-inhibitor complex (EIC) levels were determined in EDTA-plasma samples of 40 patients with connective tissue disease by a double antibody immuno-assay technique. In active rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), EIC levels were significantly higher than in the normal controls (P less than 10(-8) and fell on remission. The mean EIC level in active RA was significantly greater than in inactive disease (P = 0.0001) but there was no statistically significant difference between the EIC levels in the acute and inactive disease states in SLE (P = 0.49). In active RA, there was a positive correlation between EIC levels and white blood cell count (WBC) but not with erythrocyte sedimentation rate (ESR). In SLE there was no significant correlation between EIC levels and ESR or WBC. EIC measurement may be useful in the objective assessment of activity in RA.