Serum adenosine deaminase activity is increased in systemic lupus erythematosus patients and correlated with disease activity.

Adenosine deaminase (ADA) has been found to be involved in autoimmune disease progression. To assess the potential application of serum ADA activity in diagnosing systemic lupus erythematosus (SLE) and evaluating SLE disease activity, we investigated the serum ADA activity of 120 SLE patients and 120 healthy controls in the present study. The results showed that serum ADA activity in SLE patients was significantly increased (median (IQR) = 14 (11-19) U/L) compared with that in healthy controls (median (IQR) = 8 (7-10) U/L). Based on a receiver operating characteristic curve analysis, the optimal cut-off value for using serum ADA activity to diagnose SLE patients was 10.5 U/L (specificity, 84.2%; sensitivity, 78.3%). The diagnostic performance of serum ADA activity for SLE patients was better than that of other conventional haematology markers. Moreover, serum ADA activity displayed an increasing trend with increasing SLE disease activity. Spearman's correlation analysis showed that serum ADA activity was positively correlated with SLE disease activity. These findings suggest that serum ADA activity could be a diagnostic marker for SLE; moreover, measuring serum ADA activity may be helpful for evaluating and monitoring the disease activity of SLE patients.