Cytokines in Autoimmunity

Abstract

Cytokines have been demonstrated to play a major role in the development of autoimmunity and induction of the two levels of autoimmune responses. The relative contribution of T-helper (CD4+) type 1 (TH1), or type 2 (TH2) cells is associated with the development of distinct autoimmune responses and can influence whether, or not, this response will lead to clinical disease. The TH1 pattern is characterized by over stimulation of the main cytokines IL-2 and IFN-γ, and also of TNF-α, TNF-β, GM-CSF, and IL-3. The TH2 pattern is characteristic to humoral immunity and allergic reactions, and the main cytokines produced are IL-4, IL-5, IL-6, and IL-10, but also IL-9, IL-13, TNF-α, GM-CSF, and IL-3. According to the characteristic cytokine patterns, autoimmune diseases can be divided into TH1 or TH2 patterns, or to heterogeneous cytokine-type diseases. TH1 cytokine pattern is observed in organ-specific autoimmune diseases, such as experimental allergic encephalomyelitis, multiple sclerosis, autoimmune thyroid diseases, insulin-dependent diabetes mellitus, primary biliary cirrhosis, recurrent abortions, and acute allograft rejections. TH2 cytokine pattern is observed in the pathogenesis of systemic autoimmune disorders, such as graft versus host disease, Omenn's syndrome, and atopic disorders. Heterogenous TH1/TH2 cytokine pattern occurs in autoimmune disorders, such as systemic lupus erythematosus, rheumatoid arthritis, Sjӧgren's syndrome, primary systemic vasculitis, and myasthenia gravis.