Expression of BAFF and BAFF-R in the synovial tissue of patients with rheumatoid arthritis.

Objective: The elevated expression of B‐cell‐activating factor belonging to the TNF family (BAFF) is associated with systemic autoimmune disease, including rheumatoid arthritis (RA). The present study was undertaken to determine the distribution of BAFF and its receptor BAFF‐R in the cells residing in the rheumatoid synovium.Methods: The expression of BAFF and BAFF‐R in synovial tissues obtained from 12 RA patients was examined by immunohistochemistry and flow cytometry. The mRNA expression of these molecules was determined by reverse transcriptase polymerase chain reaction (RT‐PCR). Soluble BAFF levels were measured with an enzyme‐linked immunosorbent assay (ELISA). Fibroblast‐like synoviocytes (FLS) purified from the RA (RA‐FLS) were co‐cultured with peripheral B cells. The degree of apoptosis in the B cells was measured to assess the effects on the viability of the B cells.Results: The RA synovium showed focal or diffuse infiltration of mononuclear cells (MNCs), and one specimen showed germinal centre ...