Abstract:

Objective To discuss the changes of adenosine deaminase 2 （ADA2） activity in the serum of the systemic lupus erythematosus （SLE） patients， and to clarify its clinical value in the diagnosis and disease assessment of the SLE patients. Methods According to the inclusion and exclusion criteria， 69 SLE patients （SLE group） and 69 healthy controls （control group） were enrolled as study subjects. The disease activity of SLE patients was evaluated by SLE Disease Activity Index （SLEDAI）. The ADA2 activity in the serum of the subjects in both groups was detected. The patients were further divided into subgroups based on the presence or absence of the following clinical symptoms： arthritis， myositis， hematuria， proteinuria， pyuria， alopecia， new rash， mucosal ulcer， pleuritis， hypocomplementemia， elevated anti-double-stranded DNA （anti-dsDNA） antibody， thrombocytopenia， and leukopenia. The differences in serum ADA2 activity between joint symptomatic group and joint asymptomatic group were analyzed. The diagnostic efficacy of serum ADA2 activity was evaluated by receiver operating characteristic （ROC） curve analysis. The correlation between ADA2 activity and disease activity in the SLE patients was analyzed by Spearman correlation analysis. Results Compared with control group， the ADA2 activity in the serum of the patients in SLE group was significantly increased （P<0.01）. The ROC analysis results showed that when the cut-off value of ADA2 activity was set at 8.5 U·L^-1， the diagnostic performance was optimal， with an area under the curve （AUC） of 0.879 （95%CI： 0.817-0.940）， the specificity was 89.86%， and the sensitivity was 75.36%. The serum ADA2 activity was positively correlated with disease activity in the SLE patients （r=0.32， P=0.007）. The subgroup analysis of clinical symptoms results showed that the serum ADA2 activity in the SLE patients with symptoms was significantly higher than that in the SLE patients without symptoms （P<0.01）. No significant differences were observed in serum ADA2 activity between the SLE patients with and without myositis， hematuria， proteinuria， pyuria， alopecia， new rash， mucosal ulcer， pleuritis， hypocomplementemia， elevated anti-dsDNA antibody， thrombocytopenia， or leukopenia （P>0.05）. Conclusion The serum ADA2 activity is increased in the SLE patients and can serve as a diagnostic marker for SLE. Serum ADA2 activity is positively correlated with disease activity and is associated with arthritis in the SLE patients， suggesting its potential as an indicator for disease assessment and monitoring.

Key words: Adenosine deaminase 2, Systemic lupus erythematosus, Diagnosis, Disease activity, Receiver operating characteristic curve