Cytokine
Cytokines are large and heterogeneous group of small proteins, which are released by different groups of cells and mediate all aspect of innate and adaptive immunity. They induce responses through binding to specific receptors. Most cytokine act close to where they are produced, either on the same cell that secretes the cytokine (autocrine action) or on a nearby cell (paracrine action). When produced in large amounts, Cytokines may enter the circulation and act at distance from the site of production (endocrine action). One cytokine can act on diverse cell types and have multiple biologic effects (pleiotropism). Conversely multiple cytokines can have the same action and are said to be redundant.
Macrophage release divers group of cytokines in response to pathogen include TNF-α, interleukin-1β, IL-6, IL-12 and IL-8. TNF-α and IL-1β and IL-6 are members of proinflammatory cytokines, which are more important in acute inflammation and have both local and distant effects. IL-12 active NK cells and drives the differentiation of CD4 T cell to TH1cells.
TNF-α, which is secreted by active macrophages, increases vascular permeability, which leads to entry of IgG and complement components to the infected tissues. It also induces necessary adhesion molecules on endothelial cells, which leads recruitment of leukocytes especially neutrophils into the site of inflammation. It is done by externalization of endothelial cell granules called Weibel-Palade bodies, which contain preformed P-selectin molecules. The other effect of TNF-α is stimulating endothelial cells to express proteins that trigger blood clotting in local small vessels, thus cutting of the blood flow. This is important in preventing the pathogen from entering the bloodstream and spreading to organs all over the body. TNF-α also has a role in stimulating the migration of dendritic cells from their sites in peripheral tissues and in their maturation into nonphagocytic but highly co-stimulatory antigen-presenting
Macrophage release divers group of cytokines in response to pathogen include TNF-α, interleukin-1β, IL-6, IL-12 and IL-8. TNF-α and IL-1β and IL-6 are members of proinflammatory cytokines, which are more important in acute inflammation and have both local and distant effects. IL-12 active NK cells and drives the differentiation of CD4 T cell to TH1cells.
TNF-α, which is secreted by active macrophages, increases vascular permeability, which leads to entry of IgG and complement components to the infected tissues. It also induces necessary adhesion molecules on endothelial cells, which leads recruitment of leukocytes especially neutrophils into the site of inflammation. It is done by externalization of endothelial cell granules called Weibel-Palade bodies, which contain preformed P-selectin molecules. The other effect of TNF-α is stimulating endothelial cells to express proteins that trigger blood clotting in local small vessels, thus cutting of the blood flow. This is important in preventing the pathogen from entering the bloodstream and spreading to organs all over the body. TNF-α also has a role in stimulating the migration of dendritic cells from their sites in peripheral tissues and in their maturation into nonphagocytic but highly co-stimulatory antigen-presenting