[Serum adenosine deaminase as a parameter for activity in sarcoidosis]

Adenosin deaminase (ADA) is an enzyme of purine metabolism and reflects the involvement of the cellular immune system. The ADA serum levels were tested in 130 healthy blood donors, and in 98 patients (pts) with sarcoidosis; 59 pts with active and 39 pts with inactive sarcoidosis. These two patient groups were separated into treated and untreated; the active group was divided into an acute onset group (12 pts) and a group with chronic disease (47 pts). The disease activity was determined on the basis of clinical symptoms, chest x-ray and lung function tests. ADA was compared to angiotensin converting enzyme(ACE), neopterin (NPT), and soluble interleukin-2 receptor (sIL-2 R). ADA activity was measured colorimetrically according to a method of Giusti with slight modifications. ACE was determined by a commercial kit by Fujerbio, Japan. NPT and sIL-2 R were evaluated by commercial enzyme-linked immunosorbent assays. The ADA activity in controls was 18.8 +/- 3.8 U/I (mean +/- SD), the upper normal serum range (mean +/- 2SD) was established at 26.4 U/I. Serum ADA levels in the group with active sarcoidosis (33.5 +/- 14.3 U/I, p < 0.0001) were significantly higher than those in healthy controls and in inactive disease (19.6 +/- 5.8 U/I, p < 0.0001). Sensitivity and specificity were: ADA 75%/92%, ACE 49%/85%, NPT 78%/74%, sIL-2 R 81%/57%.

Our findings demonstrate that the course of the disease can be monitored by measurement of the serum ADA. In comparison to the other parameters, measurement of the serum ADA indicates a greater discrimination between active and inactive disease.