The participation of IL-8 in the synovial lesions at an early stage of rheumatoid arthritis

Synovial tissues from Rheumatoid Arthritis (RA) were divided into three gro ups based on their histopathological findings and compared for their expres sion of IL-8 and monocyte chemotactic and activating factor (MCAF) by using immunohistochemistry and in situ hybridization. The Bevels of IL-8 as well as those of MCAF were markedly higher in the synovial fluid from RE joints . Synovial lining cells (SLC) and macrophages had an ability to produce IL- 8 at an early phase of the disease. The presence of MCAF was restricted, in macrophages at this stage. On the other hand, the production of IL-8 as we ll as MCAF were prominent in most components of the joints such as SLC, mig rated monocytes, sublining fibroblastoid cells, endothelial cells or migrat ed neutrophils at an active phase. The expression of IL-8 or MCAF was low i n fibrotic synovitis of RA. These data indicate that IL-8 generated from SL C and macrophages may participate to the inflammatory process in the early synovitis of RA.(C) 1999 Tohoku University Medical Press.