Cytokine expression and networks in rheumatoid arthritis: rationale for anti-TNF alpha antibody therapy and its mechanism of action.

The cloning of cytokine cDNAs has permitted the analysis of cytokine expression in diseased sites such as rheumatoid joints. A very wide range of cytokines were detected, mostly with proinflammatory activities. From the analysis of cytokine regulation in rheumatoid joint cell cultures using neutralizing anti-cytokine antibodies, it was found that blockade of TNF alpha reduced the production of other proinflammatory cytokines. Hence TNF alpha was a potential therapeutic target. This concept was tested successfully in collagen induced arthritis in mice and led to clinical trials of anti-TNF alpha antibody in rheumatoid arthritis (RA) in humans. The mechanism of action of anti-TNF alpha will be discussed.