[Cytokines]

Cytokines are relatively small polypeptides that are essential components of inflammatory reactions and immunologic processes. They are produced by a great variety of cells. The molecular biology revolution of the seventies and eighties has enabled investigators to elucidate the structure of cytokines and to unravel their spectrum of activity. Cytokines play a central role in the pathogenesis of infectious diseases and in the regulation of the immune system. Tumor necrosis factor (TNF) and interleukin-I (IL-I) were found to be responsible for most of the symptoms of infectious diseases, from fever to septic shock. In addition, TNF and IL-I are probably indispensable for repair of tissue damage. IL-2 is the pivotal cytokine for the regulation of the immune system; it is produced by CD4-positive T-cells and essential for the proliferation of T-lymphocytes in general and crucial for the induction of cytotoxic T-cells. Studies to define the therapeutic possibilities of cytokines are in progress.