Adaptive Immune System - Overview - Revision history

Bara at 16:11, 2 July 2012

2012-07-02T16:11:47Z

Rjfrancisrvc: /* Cellular response: Proliferation and Differentiation */

2012-05-22T14:13:43Z

Cellular response: Proliferation and Differentiation

Rjfrancisrvc: /* Antigen Presenting Cells */

2012-05-22T13:58:48Z

Antigen Presenting Cells

Rjfrancisrvc: /* Cellular response: Proliferation and Differentiation */

2012-05-18T13:19:18Z

Cellular response: Proliferation and Differentiation

Rjfrancisrvc: /* Antigen Recognition */

2012-05-18T13:17:52Z

Antigen Recognition

Rjfrancisrvc: /* Cellular response: Proliferation and Differentiation */

2012-05-18T13:16:36Z

Cellular response: Proliferation and Differentiation

Rjfrancisrvc: /* Cellular response: Proliferation and Differentiation */

2012-05-18T13:16:01Z

Cellular response: Proliferation and Differentiation

Rjfrancisrvc: /* Cellular response: Proliferation and Differentiation */

2012-05-18T13:14:09Z

Cellular response: Proliferation and Differentiation

Bara at 19:11, 16 March 2012

2012-03-16T19:11:51Z

Bara: Text replace - "[[Lymphocytes|" to "[[Lymphocytes - Introduction|"

2010-08-18T12:39:55Z

Text replace - "[[Lymphocytes|" to "[[Lymphocytes - Introduction|"

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 ==Introduction==
 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.
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 <br><br>
 {{Jim Bee 2007}}
 [[Category:Adaptive Immune System]]

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

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 *[[T cell differentiation#Antigen Presentation by Dendritic Cells|Interdigitating Dendritic Cells]]
 **Only IDCs can incite a primary response in naive T-cells
-*[[Helper CD4+|CD4+ Tcells]]
+*[[Helper CD4+|CD4<sup>+</sup> Tcells]]
 *[[B cells|B-cells]]

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 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-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>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#B Cells|B cell]] response''

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 [[Lymphocytes#T Cells|T cell]] receptors ('''TCR''') recognise '''antigen fragments''' (that is digestion products) on the '''surface of cells''', whereas [[Lymphocytes#B Cells|B cell]] receptors ('''BCR''') bind '''whole antigen''' in the '''extracellular fluid'''.  [[Lymphocytes#T Cells|T cells]] only "see" antigen when it is presented by [[Major Histocompatability Complexes|'''MHC''']] (Major Histocompatibility Complex) on the cell surface.  Antigen digestion and presentation is one of the major functions of the [[T cell differentiation#Antigen Presentation by Dendritic Cells|'''dendritic cells''']] (circulating [[Monocytes|monocytes]]) and '''[[Macrophages|macrophages]]'''.  These are referred to as '''Antigen-Presenting Cells''' (APCs).
-Naive B-cells express [[Immunoglobulin D|IgD]] and [[Immunoglobulin M|IgM]] on their cell surfaces, which bind antigen as it is washed into lymph tissue with the afferent lymph fluid.  Antigen is presented to [[Lymphocytes#B Cells|B cells]] by [[B cell differentiation#Antigen Presentation by Follicular Dendritic Cells|'''follicular dendritic cells''' (FDCs)]], which are also classed as APCs.  [[B cell differentiation#Antigen Presentation by Follicular Dendritic Cells|FDCs]] can endocytose antigen directly from the afferent lymph or receive them from [[Lymphocytes#Helper CD4+|CD4+ T-cells]].
+Naive B-cells express [[Immunoglobulin D|IgD]] and [[Immunoglobulin M|IgM]] on their cell surfaces, which bind antigen as it is washed into lymph tissue with the afferent lymph fluid.  Antigen is presented to [[Lymphocytes#B Cells|B cells]] by [[B cell differentiation#Antigen Presentation by Follicular Dendritic Cells|'''follicular dendritic cells''' (FDCs)]], which are also classed as APCs.  [[B cell differentiation#Antigen Presentation by Follicular Dendritic Cells|FDCs]] can endocytose antigen directly from the afferent lymph or receive them from [[Lymphocytes#Helper CD4+|CD4<sup>+</sup> T-cells]].
 ===Cellular response: Proliferation and Differentiation===

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 ===Antigen Recognition===
-"Antigen" refers to the parts of a foreign organism recognisable by the adaptive immune system.  Typically, these are structural proteins, such as the spike proteins of viruses.  Antigens can be huge, and are more often identified by '''epitopes''', or smaller fragments of the folded proteins.  As such, a single antigen can be recognised by multiple antigen receptors.  [[Immunoglobulins|Antibody]] has evolved to recognise a dizzying array of antigen epitopes.  Antigen can be picked up by [[Lymphocytes|lymphocytes]] in the lymph tissues ([[Lymphocytes#T Cells|T cells]] and [[Lymphocytes#B Cells|B cells]]) or the blood stream ([[Lymphocytes#T Cells|T cells]] only).
+"Antigen" refers to the parts of a foreign organism recognisable by the adaptive immune system.  Typically, these are structural proteins, such as the spike proteins of viruses.  Antigens can be huge, and are more often identified by '''epitopes''', or smaller fragments of the folded proteins.  As such, a single antigen can be recognised by multiple antigen receptors.  [[Immunoglobulins|Antibody]] has evolved to recognise a dizzying array of antigen epitopes.  Antigen can be picked up by [[Lymphocytes - Introduction|lymphocytes]] in the lymph tissues ([[Lymphocytes#T Cells|T cells]] and [[Lymphocytes#B Cells|B cells]]) or the blood stream ([[Lymphocytes#T Cells|T cells]] only).
 [[Lymphocytes#T Cells|T cell]] receptors ('''TCR''') recognise '''antigen fragments''' (that is digestion products) on the '''surface of cells''', whereas [[Lymphocytes#B Cells|B cell]] receptors ('''BCR''') bind '''whole antigen''' in the '''extracellular fluid'''.  [[Lymphocytes#T Cells|T cells]] only "see" antigen when it is presented by [[Major Histocompatability Complexes|'''MHC''']] (Major Histocompatibility Complex) on the cell surface.  Antigen digestion and presentation is one of the major functions of the [[T cell differentiation#Antigen Presentation by Dendritic Cells|'''dendritic cells''']] (circulating [[Monocytes|monocytes]]) and '''[[Macrophages|macrophages]]'''.  These are referred to as '''Antigen-Presenting Cells''' (APCs).