Acute inflammation is accompanied by changes in the concentrations of several plasma proteins. Cytokines play a crucial role in the regulation of inflammatory events. Inflammatory disorders such as rheumatoid arthritis are characterized by an overproduction of several cytokines including interleukin-6 (IL-6). Recent data suggest that IL-6 and other members of the IL-6-cytokine family have anti-inflammatory and immunosuppressive properties, and therefore may negatively regulate inflammatory processes.