Increased soluble CD72 in systemic lupus erythematosus is in association with disease activity and lupus nephritis

B cell receptor (BCR) -mediated signals are enhanced when CD72 expression is deficient on B cells in autoimmune diseases. The significance of soluble CD72 (sCD72) has not been elucidated. METHODS: Soluble CD72 was analyzed in the serum of 159 SLE patients, 40 rheumatoid arthritis (RA) patients, and 100 healthy individuals. Correlations between sCD72 and SLE disease activity (SLEDAI) were assessed. RESULTS: Soluble CD72 was found increased in SLE patients, when compared to both RA patients and healthy individuals (20.2 ± 1.2 ng/ml; 10.6 ± 4.6 ng/ml and 7.2 ± 3.3 ng/ml; p < 0.001). Soluble CD72 level was significantly higher in SLE patients with renal involvement than in patients without (31.8 ± 2.3 ng/ml vs 13.9 ± 0.9 ng/ml; p < 0.001) and also with the presence of auto-antibodies. CONCLUSION: Soluble CD72 is significantly increased in SLE patients mainly in those with renal involvement. Increased sCD72 may become a potential biomarker for renal involvement in SLE.