Changes

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+, and naive circulating [[Lymphocytes#T Cells|T cells]] will differentiate upon interaction with antigen to become either [[Lymphocytes#Cytotoxic CD8+|'''CD8+ (cytotoxic)''']] or [[Lymphocytes#Helper CD4+|'''CD4+ (helper)''']] [[Lymphocytes#T Cells|T cells]]. [[[[Lymphocytes#Helper CD4+|CD4+ T-cells]] will initially become CD4-TH₀ cells, and must differentiate to [[T cell differentiation#TH1 Cells|TH₁]] or [[T cell differentiation#TH2 Cells|TH₂]] depending on the whim of the adaptive response.  TH₁ and TH₂ cells carry out different types of responses: TH₁ is responsible for enhancing the [[Macrophages|macrophage]] response, whereas TH₂ cells enhance the [[Lymphocytes#B Cells|B cell]] antibody production.  Typically, animals produce a balanced response of TH₁ and TH₂ 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+, and naive circulating [[Lymphocytes#T Cells|T cells]] will differentiate upon interaction with antigen to become either [[Lymphocytes#Cytotoxic CD8+|'''CD8+ (cytotoxic)''']] or [[Lymphocytes#Helper CD4+|'''CD4+ (helper)''']] [[Lymphocytes#T Cells|T cells]]. [[Lymphocytes#Helper CD4+|CD4+ T-cells]] will initially become CD4-TH₀ cells, and must differentiate to [[T cell differentiation#TH1 Cells|TH₁]] or [[T cell differentiation#TH2 Cells|TH₂]] depending on the whim of the adaptive response.  TH₁ and TH₂ cells carry out different types of responses: TH₁ is responsible for enhancing the [[Macrophages|macrophage]] response, whereas TH₂ cells enhance the [[Lymphocytes#B Cells|B cell]] antibody production.  Typically, animals produce a balanced response of TH₁ and TH₂ 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#B Cells|B cell]] response''

*''[[Lymphocytes#B Cells|B cell]] response''

*Prof Dirk Werling DrMedVet PhD MRCVS

*Prof Dirk Werling DrMedVet PhD MRCVS

[[Category:Adaptive Immune System]]

[[Category:Adaptive Immune System]]