In conclusion, IL-1 has multiple biologic activities relevant to rheumatic diseases. It mediates the acute-phase response, and exerts control over many metabolic functions of connective tissue, including muscle, bone, cartilage, synovium, and endothelium. IL-1 also has a profound effect on leukocyte function. Although few clinical studies have been reported, there is suggestive evidence that IL-1 plays a role in the pathogenesis of arthritis, scleroderma, SLE and vasculitis. That drugs useful in the therapeutic management of these conditions influence IL-1 activity provides indirect support for the involvement of IL-1 in pathogenesis. Clearly, further studies are needed in this area. With the recent development of recombinant preparations of IL-1, further investigation of IL-1 in connective tissue metabolism and clinical rheumatic disease can be carried out. Finally, the future development of pharmacologic agents specifically designed to alter IL-1 responses may allow specifically targeted therapy for rheumatic diseases.