[B lymphocyte stimulator (BLyS/BAFF) level in sera of patients with lupus].

Background: B lymphocyte stimulator (BLyS/BAFF) is an endogenous protein that plays an important role in the differentiation and maduration of B lymphocytes. Enhanced levels of BLyS have been reported in lupus and other rheumatic diseases.

Methods: Serum samples from 92 lupus patients (94% females, median age 35.5 years) and 106 controls (50 healthy donors, 38 with rheumatoid arthritis, 18 with scleroderma) were analyzed for BLyS. The cutoff of BLyS ˃1.98 ng/ml corresponds to the 95th percentile from the healthy donors. Antibodies against native DNA and disease activity also were evaluated in lupus patients. During follow up, BLyS levels in 32 patients showed heterogeneity.

Results: The median level of BLyS in 92 lupus patients was 1.9 ng/mL (range 0.4-5.3), compared to 1.30, 1.35, and 1.35 ng/mL in healthy donors, rheumatoid arthritis, and scleroderma, respectively. Thirty-nine (42%) out of 92 patients had elevated levels of BLyS (median 2.8 ng/mL). A moderate correlation between titers of anti-DNA antibody (r=0.34) and Mex-SLEDAI (r=0.45) was found. The monitoring of 32 patients showed persistently high levels, or normal or intermittent variations of BLyS.

Conclusion: The BLyS level is increased in some lupus patients. There was a moderate correlation with titers of anti-DNA antibody and disease activity. The monitoring of 32 patients showed heterogeneous levels of BLyS.