Spontaneous release of angiotensin converting enzyme and interleukin 1 beta from peripheral blood monocytes from patients with rheumatoid arthritis under a serum free condition.

Angiotensin converting enzyme (ACE) and interleukin 1 activities were assayed simultaneously in the serum free medium from the unstimulated peripheral blood monocytes from 32 patients with rheumatoid arthritis (RA), 11 patients with osteoarthritis, and 25 normal controls matched for age and sex. Angiotensin converting enzyme activity was raised in most (29/32) patients with RA and interleukin 1 activity (most of which was interleukin 1 beta) was enhanced in 11/32 patients with RA, while monocytes from only two patients with osteoarthritis, but from none of the controls, secreted a small amount of ACE alone in the culture condition. Monocytes from patients with early RA (disease duration less than 3 years) released significantly more ACE and interleukin 1 than those from late stage RA (disease duration greater than or equal to 3 years).