Significant elevation of the levels of B-cell activating factor (BAFF) in patients with sarcoidosis.

B-cell activating factor (BAFF) plays an important role in the survival and differentiation of B-cells and production of antibodies. Recent studies show that the serum BAFF levels are elevated in patients with sarcoidosis; however, they have not studied the relationship of the finding with the clinical features of the disease. The purpose of the present study is to analyze the BAFF and to elucidate the relationship between BAFF levels and the disease activity or severity of sarcoidosis. Eighty-eight patients with sarcoidosis and 21 healthy volunteers were enrolled in the present study. The BAFF levels were measured by an enzyme-linked immunosorbent assay. To assess the disease severity, we examined the number of affected organs, Schadding stages, respiratory function impairment (RFI), and the scoring system developed by Wasfi et al. The serum BAFF levels in sarcoidosis patients were significantly higher than those in healthy volunteers (median 1553.0 vs 984.6 pg/ml, p < 0.001). There were positive correlations between the serum BAFF level and disease activity markers. In addition, there were positive correlations between the BAFF levels and the disease severity score in both the serum (R = 0.367, p < 0.001) and bronchoalveolar lavage fluid (BALF) (R = 0.376, p < 0.001). This study demonstrated that the BAFF levels in both the serum and BALF were positively correlated with the disease activity markers and disease severity. BAFF may be useful as an indicator of both the disease activity and severity.