Contemporary Topics in Cytokine Investigation

Cytokines are numerous factors, which activate proliferation and differentiation of body cells. Main cell-producers of cytokines belong to T helper cells and macrophages, which accomplish key role in supporting of acquired and innate immunity. Immune response can't be developed without constant lymphocyte renewing. Stem cell (CD34-positive cells) proliferation may be supported by IL-1, -3, -6 and -11 as well as by recently having become known stem cell factor (SCF). In antigen presentation to T helpers and cytotoxic cells the great importance has the expression of class I and II histocompatibility molecules, which is regulated by IL-4, -6, TNF and IFNgamma. Antigen processing in macrophages is associated with production of IL-1, -6 and TNF. Proliferation of antigen-specific T and B lymphocytes, forming clones to various antigenic epitopes, is stimulated by IL-1, -2, -4, -6, -7, -10, -12, -15 and TNF. It should be noted that B lymphocyte proliferation is provided predominantly by IL-1, -4, -6, -10, -13, meanwhile T cell growth - by IL-1, -2, -6, -7, -12, -15. Th1 differentiation from precursors occurs as a result of action of IL-2, -12, -18, which potentiate production of IFNgamma that is the key mediator in this process. The differentiation of Th2 is determined by IL-4. The competition for prevalent growth of one or another Th clones is observed during of this differentiation. So, IL-4 inhibits Th1 proliferation, induced by IL-2, meanwhile IL-12 suppresses IL-4 dependent IgE synthesis.