Serum BAFF levels and skin mRNA expression in patients with Behçet's disease.

OBJECTIVE: Serum levels of the B-cell activating factor in the tumor necrosis factor family (BAFF), a potent contributor to B-cell survival, are elevated in patients with systemic autoimmune diseases. The objective of this study was to determine serum BAFF levels and to link the results to the clinical features in patients with skin manifestations.
METHODS: Serum BAFF levels were examined by an enzyme-linked immunosorbent assay (ELISA) in 42 patients with BD (16 with active disease), 20 healthy controls, and in 20 patients with systemic lupus erythematosus (SLE) and 15 patients with multiple sclerosis (MS), who served as the disease control groups. Expression of BAFF messenger RNA (mRNA) in the skin was quantified by a real-time reverse transcription-polymerase chain reaction; the expression of BAFF receptor (BAFF-R) on CD19+ B cells was assessed by flow cytometry; and ELISA was used to evaluate the production of IgG, interleukin-6 (IL-6) and IL-10 by isolated B cells.
RESULTS: Serum BAFF levels were elevated in patients with active BD compared to the healthy controls, and correlated positively with the extent of skin lesions. Disease remission was accompanied by decreased BAFF levels. SLE patients had the highest serum BAFF levels. Skin biopsies showed BAFF mRNA expression to be up-regulated in active BD patients. BAFF-R expression on B cells was increased in BD patients with vasculitis. Furthermore, in BD patients the ability to produce IgG and IL-6 (but not IL-10) was enhanced in BAFF-stimulated B lymphocytes.
CONCLUSION: These results suggest that BAFF and its signalling in B cells contribute to B cell abnormalities and the development of skin disease in patients with BD.