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→Innate Immunity
==Innate Immunity==
==Innate Immunity==
[[File:Helmith Killing.png|300px|right|thumb|Helmith Killing - R.J.Francis, RVC 2012]]
The first line of defence against parasitic infection are the effector mechanisms of the innate immune system. The '''[[Macrophages|macrophages]]''' are important players in the defence against extracellular parasites. This is because macrophages are able to secrete [[Cytokines|cytokines]] as well as perform [[Phagocytosis|phagocytosis]]. In this they can act as 'killer cells' through antibody-dependent cell-mediated cytotoxicity, for example specific [[Immunoglobulins|IgG]]/[[Immunoglobulins|IgE]] enhances the ability of macrophages to kill schistosomules through the interaction of Fc receptors on the surface of the macrophage. Of the secreted cytokines, the secretion of TNFα is of particular importance. This is because TNFα activates other macrophages and can have toxic effects in high amounts. TNFα also renders hepatocytes resistant to malarial infection when in conjunction with IL-1. Cytokine secretion (in particular IFNγ) can also enhance killing by mechanisms using free radicals and O<sub>2</sub>-independent toxins (e.g. nitric oxide).
The first line of defence against parasitic infection are the effector mechanisms of the innate immune system. The '''[[Macrophages|macrophages]]''' are important players in the defence against extracellular parasites. This is because macrophages are able to secrete [[Cytokines|cytokines]] as well as perform [[Phagocytosis|phagocytosis]]. In this they can act as 'killer cells' through antibody-dependent cell-mediated cytotoxicity, for example specific [[Immunoglobulins|IgG]]/[[Immunoglobulins|IgE]] enhances the ability of macrophages to kill schistosomules through the interaction of Fc receptors on the surface of the macrophage. Of the secreted cytokines, the secretion of TNFα is of particular importance. This is because TNFα activates other macrophages and can have toxic effects in high amounts. TNFα also renders hepatocytes resistant to malarial infection when in conjunction with IL-1. Cytokine secretion (in particular IFNγ) can also enhance killing by mechanisms using free radicals and O<sub>2</sub>-independent toxins (e.g. nitric oxide).
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