495
edits
Changes
→Cell-Mediated
==Cell-Mediated==
==Cell-Mediated==
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''.
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<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).
*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 [[Major Histocompatability Complexes|MHC]] class I), while CD8<sup>+</sup> cells are required to mediate immunity against the liver stage (hepatocytes do not express [[Major Histocompatability Complexes|MHC]] class II).
*T<sub>H</sub>1 cells are required to fight intracellular protozoa - the release of Interferon-γ (IFNγ) activates macrophages to kill the protozoa residing within them
*T<sub>H</sub>1 cells are required to fight intracellular protozoa - the release of Interferon-γ (IFNγ) activates macrophages to kill the protozoa residing within them
*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 Interleuken-5 (IL-5), predominate. IL-5 is the [[Cytokines|cytokine]] responsible for the eosinophilia associated with parasite infections.
*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 Interleuken-5 (IL-5), predominate. IL-5 is the [[Cytokines|cytokine]] responsible for the eosinophilia associated with parasite infections.