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| ==Adaptive Immunity== | | ==Adaptive Immunity== |
− | Although the innate immune system provides an effective first line of defence, T cells are fundamental in the development of immunity, demonstrated using T-cell deprived mice that fail to resolve otherwise non-lethal infections of, for example, ''T. cruzi''. | + | Although the innate immune system provides an effective first line of defence, [[T cells|T cells]] are fundamental in the development of immunity, demonstrated using T-cell deprived mice that fail to resolve otherwise non-lethal infections of, for example, ''T. cruzi''. |
− | *Both CD4+ and CD8+ cells are required for protection, e.g CD4+ cells protect against the blood stage of a Plasmodium infection (erythrocytes do not express MHC class I), while CD8+ cells are required to mediate immunity against the liver stage (hepatocytes do not express MHC class II). | + | *Both CD4<sup>+</sup> and CD8<sup>+</sup> cells are required for protection, e.g CD4<sup>+</sup> cells protect against the blood stage of a Plasmodium infection (erythrocytes do not express MHC class I), while CD8<sup>+</sup> cells are required to mediate immunity against the liver stage (hepatocytes do not express MHC class II). |
− | *Th1 cells are required to fight intracellular protozoa- the release of IFN-γ activates macrophages to kill the protozoa residing within them | + | *T<sub>H</sub>1 cells are required to fight intracellular protozoa - the release of IFN-γ activates macrophages to kill the protozoa residing within them |
− | *Helminth infections require both Th1 and Th2 responses, e.g. during ''S. mansoni'' the secretion of IFN-γ by Th1 cells activates mechanisms that destroy larvae in the lungs, although the Th2 subset, secreting IL-5, predominate | + | *Helminth infections require both T<sub>H</sub>1 and T<sub>H</sub>2 responses, e.g. during ''S. mansoni'' the secretion of IFNγ by T<sub>H</sub>1 cells activates mechanisms that destroy larvae in the lungs, although the T<sub>H</sub>2 subset, secreting IL-5, predominate. IL-5 is responsible for the eosinophilia associated with parasite infections. |
− | *Th2 cells are required for the destruction of intestinal worms, where they induce mucosal mast cells and interact with eosinophils | + | *T<sub>H</sub>2 cells are required for the destruction of intestinal worms, where they induce mucosal mast cells and interact with [[Eosinophils|eosinophils]] |
| While cell-mediated immunity is important in tissue infections, such as Leishmania, specific antibodies are important in controlling parasites that live in the bloodstream, e.g. malaria. Mechanisms of antibody-mediated immunity include: | | While cell-mediated immunity is important in tissue infections, such as Leishmania, specific antibodies are important in controlling parasites that live in the bloodstream, e.g. malaria. Mechanisms of antibody-mediated immunity include: |
| *Directly damaging protozoa | | *Directly damaging protozoa |