| Adaptive immunity is a defence system built on specific cellular targeting. It takes time for the immune system to develop its weaponry (up to 96 hours after infection), but ultimately the adaptive response is far more effective because of its precision. | | Adaptive immunity is a defence system built on specific cellular targeting. It takes time for the immune system to develop its weaponry (up to 96 hours after infection), but ultimately the adaptive response is far more effective because of its precision. |
| Once [[Lymphocytes#T Cells|T cells]] recognise antigen presence in the tissues, they go into action. Their first response is always to recruit help, which is accomplished by returning to the nearest [[Lymph Nodes - Anatomy & Physiology|lymph node]] to carry out clonal expansion. Daughter [[Lymphocytes#T Cells|T cells]] are created with identical TCRs in order to recognise the identified antigen. These daughter cells are then returned to the circulation via the efferent lymph. | | Once [[Lymphocytes#T Cells|T cells]] recognise antigen presence in the tissues, they go into action. Their first response is always to recruit help, which is accomplished by returning to the nearest [[Lymph Nodes - Anatomy & Physiology|lymph node]] to carry out clonal expansion. Daughter [[Lymphocytes#T Cells|T cells]] are created with identical TCRs in order to recognise the identified antigen. These daughter cells are then returned to the circulation via the efferent lymph. |
− | [[Lymphocytes#T Cells|T cells]] can differentiate three different ways, based on their Cluster of Differentiation (CD) number. All [[Lymphocytes#T Cells|T cells]] are CD3<sup>+</sup>, and naive circulating [[Lymphocytes#T Cells|T cells]] will differentiate upon interaction with antigen to become either [[Lymphocytes#Cytotoxic CD8+|'''CD8<sup>+</sup> (cytotoxic)''']] or [[Lymphocytes#Helper CD4+|'''CD4<sup>+</sup> (helper)''']] [[Lymphocytes#T Cells|T cells]]. [[Lymphocytes#Helper CD4+|CD4<sup>+</sup> T-cells]] will initially become CD4<sup>+</sup>-T<sub>H</sub>0 cells, and must differentiate to [[T cell differentiation#TH1 Cells|T<sub>H</sub>1]], [[T cell differentiation#TH2 Cells|T<sub>H</sub>2]] or [[T cell differentiation#TH17 Cells|T<sub>H</sub>17]] cells depending on the whim of the adaptive response. T<sub>H</sub>1, T<sub>H</sub>2 and T<sub>H</sub>17 cells carry out different types of responses: T<sub>H</sub>1 is responsible for enhancing the [[Macrophages|macrophage]] response, whereas T<sub>H</sub>2 cells enhance the [[Lymphocytes#B Cells|B cell]] antibody production, and T<sub>H</sub>17 cells enhance the innate immune response through increased granulocyte trafficking. Typically, animals produce a balanced response of T<sub>H</sub> cells, though this can lead to pathology, as can a skewed response, depending on the nature of the foreign organism. For more on [[Lymphocytes#T Cells|T cell]] differentiation, see [[T cell differentiation|here]]. | + | [[Lymphocytes#T Cells|T cells]] can differentiate three different ways, based on their Cluster of Differentiation (CD) number. All [[Lymphocytes#T Cells|T cells]] are CD3<sup>+</sup>, and naive circulating [[Lymphocytes#T Cells|T cells]] will differentiate upon interaction with antigen to become either [[Lymphocytes#Cytotoxic CD8+|'''CD8<sup>+</sup> (cytotoxic)''']] or [[Lymphocytes#Helper CD4+|'''CD4<sup>+</sup> (helper)''']] [[Lymphocytes#T Cells|T cells]]. [[Lymphocytes#Helper CD4+|CD4<sup>+</sup> T-cells]] will initially become CD4<sup>+</sup>-T<sub>H</sub>0 cells, and must differentiate to [[T cell differentiation#TH1 Cells|T<sub>H</sub>1]], [[T cell differentiation#TH2 Cells|T<sub>H</sub>2]] or [[T cell differentiation#TH17 Cells|T<sub>H</sub>17]] cells depending on the whim of the adaptive response (T<sub>H</sub>17cells are a recent addition to this model, with research still being conducted into function). T<sub>H</sub>1, T<sub>H</sub>2 and T<sub>H</sub>17 cells carry out different types of responses: T<sub>H</sub>1 is responsible for enhancing the [[Macrophages|macrophage]] response, whereas T<sub>H</sub>2 cells enhance the [[Lymphocytes#B Cells|B cell]] antibody production, and T<sub>H</sub>17 cells enhance the innate immune response through increased granulocyte trafficking. Typically, animals produce a balanced response of T<sub>H</sub> cells, though this can lead to pathology, as can a skewed response, depending on the nature of the foreign organism. For more on [[Lymphocytes#T Cells|T cell]] differentiation, see [[T cell differentiation|here]]. |