Macrophages - Revision history

Fiorecastro at 21:05, 3 January 2023

2023-01-03T21:05:52Z

Bara at 15:39, 19 May 2012

2012-05-19T15:39:19Z

Bara: /* Immune System Regulation */

2012-05-18T17:29:15Z

Immune System Regulation

Rjfrancisrvc: /* Immune System Regulation */

2012-05-17T10:54:35Z

Immune System Regulation

Rjfrancisrvc: /* Immune System Regulation */

2012-05-09T15:47:35Z

Immune System Regulation

Rjfrancisrvc: /* Immune System Regulation */

2012-05-09T15:47:12Z

Immune System Regulation

Rjfrancisrvc: /* Immune System Regulation */

2012-05-03T11:54:16Z

Immune System Regulation

Rjfrancisrvc: /* Antigen Presentation */

2012-05-03T11:13:58Z

Antigen Presentation

Rjfrancisrvc: /* Recognition */

2012-05-03T11:12:44Z

Recognition

Rjfrancisrvc: /* Immune System Regulation */

2012-05-03T11:11:19Z

Immune System Regulation

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 {{Robert J Francis
 |date = May 17, 2012}}
 [[Category:Blood_Cells]] [[Category:Robert J Francis reviewed]]

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 ==Introduction==
-Macrophages are large, round cells that contain a central round nucleus and have abundant clear, often vacuolated, cytoplasm. Macrophages acts as sentinel cells; they have a role in destroying bacteria, protozoa and tumour cells, and release substances that act upon other immune cells. They are also responsible for clearing dead and damaged cells and tissue through the process known as efferocytosis. Macrophages are [[Phagocytosis|phagocytic]], long lived and are found throughout the body.
+[[Image:LH Macrophage Histology.jpg|thumb|right|200px|<p>'''Macrophage'''</p><sup>© Nottingham Uni</sup>]]
 ==Development==
 Macrophages are either derived from blood borne [[Monocytes|monocytes]] which have migrated into tissue and differentiated, or from dividing macrophages within the tissue.
-===Locations===
 <p>Macrophages are present throughout the body with large numbers in the [[Lymph Nodes - Anatomy & Physiology|lymph nodes]], [[Bone Marrow - Anatomy & Physiology|bone marrow]] and [[Spleen - Anatomy & Physiology|spleen]]. In connective tissue macrophages are fixed and referred to as tissue histocytes. Sentinel macrophages in the lung are called alveolar macrophages, while in the [[Liver - Anatomy & Physiology|liver]] they are called Kupffer cells. In the brain they are microglia with long cytoplasmic processes.</p>
-===Variations===
+==Variations==
-====Epithelioid cells====
+===Epithelioid cells===
-* Look like squamous epithelial cells with a pink (eosinophilic) cytoplasm and indistinct borders.
+Epithelioid cells look like squamous epithelial cells with a pink (eosinophilic) cytoplasm and indistinct borders. They may be binucleate and tend to remain in the lesion. It is thought by some people that they may not phagocytose, but instead secrete substances directed against the foreign agent.
-====Giant cells====
+===Giant cells===
-<p>Macrophages can fuse together to form giant cells (Langhan’s cells), which with their greater cytoplasmic volume and number of lysosomes are able to engulf and deal with large foreign particles/bodies. They are thought to form when two or more macrophages attempt to engulf the same organism; the resulting cell can contain between two to several hundred nuclei per cell).</p><p>The nuclei can be scattered throughout the cytoplasm, clumped in the centre in foreign body granulomas or appear in a horseshoe shape at the periphery of the cytoplasm at one end in tuberculosis and some other granulomas. In the past, the morphology of these giant cells was correlated with the agent responsible for inflammation, although the distinction is not absolute.</p>
+<p>Macrophages can fuse together to form giant cells (Langhan’s cells), which with their greater cytoplasmic volume and number of lysosomes are able to engulf and deal with large foreign particles/bodies. They are thought to form when two or more macrophages attempt to engulf the same organism; the resulting cell can contain between two to several hundred nuclei per cell).</p><p>The nuclei can be scattered throughout the cytoplasm, clumped in the centre in foreign body granulomas or appear in a horseshoe shape at the periphery of the cytoplasm at one end in [[tuberculosis]] and some other granulomas. In the past, the morphology of these giant cells was correlated with the agent responsible for [[inflammation]], although the distinction is not absolute.</p>
 ==Actions==
 ===Phagocytosis===
-<p>Macrophages are [[Phagocytosis|phagocytic]] and take up particles and cell debris by endocytosis, as well as engulfing pathogens like bacteria through the specialist function of [[Phagocytosis|phagocytosis]]. These are then present in the macrophage inside phagosomes. Lysosomes present in the cytoplasm then bind with the phagosome and release their contents which degrade/digest its contents. The degradation of the lysosomal contents occurs in much the same way as [[Neutrophils|neutrophils]] with both oxygen-dependent and oxygen-independent mechanisms.</p>
+<p>Macrophages are [[Phagocytosis|phagocytic]] and take up particles and cell debris by endocytosis, as well as engulfing pathogens like bacteria through the specialist function of [[Phagocytosis|phagocytosis]]. These are then present in the macrophage inside phagosomes. Lysosomes present in the cytoplasm then bind with the phagosome and release their contents which degrade/digest its contents. The degradation of the lysosomal contents occurs in much the same way as [[Neutrophils#Actions|neutrophils]] with both oxygen-dependent and oxygen-independent mechanisms.</p>
-====Recognition====
 <p>To function correctly macrophages need to correctly identify material that is either foreign (non-self) or which requires removal, such as damaged cells. They are able to recognise some foreign material directly (for example Lipopolysaccharide (LPS)) but in other circumstances proteins (opsonins) that bind to bacteria are required to increase the chances of successfully binding the foreign material to the macrophage. Some examples of opsonins include [[Complement|complement]] component C3bi and bound [[Immunoglobulins|antibody]].  </p>
-====Killing====
+===Killing===
 <p>This occurs using either oxygen dependant pathways or oxygen independent pathways.</p>
-<p>Oxygen dependant killing requires the production of reactive oxygen species (ROS)(O<sub>2</sub><sup>-</sup>), hydrogen peroxide (OH), reactive nitrogen species (RNS) (nitric oxide (NO)) and chlorine (Cl*) free-radicals that damage bacterial membranes (OH + Cl* = HOCl (otherwise known as bleach!)) . These reactive species are generated during a burst of respiration following [[Phagocytosis|phagocytosis]] where increased amounts of oxygen are produced. Hydrochloric acid (HCl) is also produced during this process.</p>
+<p>Oxygen dependant killing requires the production of reactive oxygen species (ROS)(O<sub>2</sub><sup>-</sup>), hydrogen peroxide (OH), reactive nitrogen species (RNS) (nitric oxide (NO)) and chlorine (Cl*) free-radicals that damage bacterial membranes (OH + Cl* = HOCl (otherwise known as bleach!)). These reactive species are generated during a burst of respiration following [[Phagocytosis|phagocytosis]] where increased amounts of oxygen are produced. Hydrochloric acid (HCl) is also produced during this process.</p>
 <p>Oxygen independent killing uses lysosomes, cathepsin (a protease) and other mechanisms. Lysozymes are particularly effective against gram positive bacteria as they hydrolyse the glycopeptide coating of the bacterial organisms. </p>
 ===Antigen Presentation===
-<p>Macrophages also act as '''antigen presenting cells''' taking antigens to lymph nodes to present to T cells. MHC II ([[Major Histocompatability Complexes|major histocompatibility complex]] II) proteins on their surface allow them to interact with helper T cells (CD4). Short peptide segments from foreign cells are presented with MHC II which activates the [[T cells|T cell]] as part of the adaptive immune response.</p>
+<p>Macrophages also act as '''antigen presenting cells''' taking antigens to lymph nodes to present to T cells. MHC II ([[Major Histocompatability Complexes|major histocompatibility complex]] II) proteins on their surface allow them to interact with helper T cells (CD4). Short peptide segments from foreign cells are presented with MHC II which activates the [[T cells|T cell]] as part of the [[Adaptive Immune System|adaptive immune]] response.</p>
 ===Immune System Regulation===
-Macrophages are important players in orchestrating the various parts of the immune response. Tissue macrophages are responsible for the trigger of the [[Innate Immune System|innate immune response]] to an injury by releasing pro-inflammatory [[Cytokines|cytokines]], in particular '''IL-1, IL-6 and TNF-α''', that are responsible for the activation of the endothelium of post-capillary venules that allows neutrophils and other immune cells to adhere and extravasate (move out of the blood). With interactions with [[Mast Cells|Mast cells]] they amplify the release of vasoactive peptides including histamine and bradykinin. The cytokines IL-1, IL-6 and TNF-α along with the vasoactive peptides are responsible for the five signs of [[Inflammation - Introduction|inflammation]]:(redness ('''rubor'''), heat ('''calor'''), swelling ('''tumor'''), and pain ('''dolor'''), often accompanied by loss of function). Systemic activation of macrophages leads to the condition known as '''septic shock'''.
+Macrophages are important players in orchestrating the various parts of the immune response. Tissue macrophages are responsible for the trigger of the [[Innate Immune System|innate immune response]] to an injury by releasing pro-inflammatory [[Cytokines|cytokines]], in particular '''IL-1, IL-6 and TNF-α''', that are responsible for the activation of the endothelium of post-capillary venules that allows neutrophils and other immune cells to adhere and extravasate (move out of the blood). With interactions with [[Mast Cells|mast cells]] they amplify the release of vasoactive peptides including histamine and bradykinin. The cytokines IL-1, IL-6 and TNF-α along with the vasoactive peptides are responsible for the five signs of [[Inflammation - Introduction|inflammation]]:(redness ('''rubor'''), heat ('''calor'''), swelling ('''tumor'''), and pain ('''dolor'''), often accompanied by loss of function). Systemic activation of macrophages leads to the condition known as '''septic shock'''.
 <p>In the latter course of inflammation, it is the blood monocytes, along with [[Dendritic Cells|dendritic cells]] that switch the immune system from innate to adaptive (see above) by interacting with CD4<sup>+</sup> T helper cells. </p>
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 ===Role in pathology===
-<p>Macrophages are seen in both [[Acute Inflammation|acute]] and [[Chronic Inflammation| chronic inflammation]].</p>  If large numbers of macrophages are found in chronic inflammatory processes, it implies the inability to eliminate the causal organism  e.g. [[:Category:Mycobacterium species|Mycobacterium (TB)]], [[:Category:Actinobacillus species|Actinobacillus]], fungi, parasites and foreign bodies.
+<p>Macrophages are seen in both [[Acute Inflammation|acute]] and [[Chronic Inflammation| chronic inflammation]].</p>  If large numbers of macrophages are found in chronic inflammatory processes, it implies the inability to eliminate the causal organism  e.g. [[:Category:Mycobacterium species|''Mycobacterium'' (TB)]], [[:Category:Actinobacillus species|''Actinobacillus'']], [[fungi]], [[parasites]] and foreign bodies.
 <br>
 {{Template:Learning
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-[[Category:Blood_Cells]] [[Category:Kate English reviewing]]
+{{Robert J Francis

@@ Line 33: / Line 33: @@
 ===Immune System Regulation===
-Macrophages are important players in orchestrating the various parts of the immune response. Tissue macrophages are responsible for the trigger of the innate immune response to an injury by releasing pro-inflammatory [[Cytokines|cytokines]], in particular '''IL-1, IL-6 and TNF-α''', that are responsible for the activation of the endothelium of post-capillary venules that allows neutrophils and other immune cells to adhere and extravasate (move out of the blood). With interactions with [[Mast Cells|Mast cells]] they amplify the release of vasoactive peptides including histamine and bradykinin. The cytokines IL-1, IL-6 and TNF-α along with the vasoactive peptides are responsible for the five signs of [[Inflammation - Introduction|inflammation]]:(redness ('''rubor'''), heat ('''calor'''), swelling ('''tumor'''), and pain ('''dolor'''), often accompanied by loss of function). Systemic activation of macrophages leads to the condition known as '''septic shock'''.
+Macrophages are important players in orchestrating the various parts of the immune response. Tissue macrophages are responsible for the trigger of the [[Innate Immune System|innate immune response]] to an injury by releasing pro-inflammatory [[Cytokines|cytokines]], in particular '''IL-1, IL-6 and TNF-α''', that are responsible for the activation of the endothelium of post-capillary venules that allows neutrophils and other immune cells to adhere and extravasate (move out of the blood). With interactions with [[Mast Cells|Mast cells]] they amplify the release of vasoactive peptides including histamine and bradykinin. The cytokines IL-1, IL-6 and TNF-α along with the vasoactive peptides are responsible for the five signs of [[Inflammation - Introduction|inflammation]]:(redness ('''rubor'''), heat ('''calor'''), swelling ('''tumor'''), and pain ('''dolor'''), often accompanied by loss of function). Systemic activation of macrophages leads to the condition known as '''septic shock'''.
 <p>In the latter course of inflammation, it is the blood monocytes, along with [[Dendritic Cells|dendritic cells]] that switch the immune system from innate to adaptive (see above) by interacting with CD4<sup>+</sup> T helper cells. </p>

@@ Line 35: / Line 35: @@
 Macrophages are important players in orchestrating the various parts of the immune response. Tissue macrophages are responsible for the trigger of the innate immune response to an injury by releasing pro-inflammatory [[Cytokines|cytokines]], in particular '''IL-1, IL-6 and TNF-α''', that are responsible for the activation of the endothelium of post-capillary venules that allows neutrophils and other immune cells to adhere and extravasate (move out of the blood). With interactions with [[Mast Cells|Mast cells]] they amplify the release of vasoactive peptides including histamine and bradykinin. The cytokines IL-1, IL-6 and TNF-α along with the vasoactive peptides are responsible for the five signs of [[Inflammation - Introduction|inflammation]]:(redness ('''rubor'''), heat ('''calor'''), swelling ('''tumor'''), and pain ('''dolor'''), often accompanied by loss of function). Systemic activation of macrophages leads to the condition known as '''septic shock'''.
-<p>In the latter course of inflammation, it is the blood monocytes, along with [[Dendritic Cells|dendritic cells]] that switch the immune system from innate to adaptive (see above) by interacting with CD4+ T helper cells. </p>
+<p>In the latter course of inflammation, it is the blood monocytes, along with [[Dendritic Cells|dendritic cells]] that switch the immune system from innate to adaptive (see above) by interacting with CD4<sup>+</sup> T helper cells. </p>
 ===Chemotaxis===

@@ Line 33: / Line 33: @@
 ===Immune System Regulation===
-Macrophages are important players in orchestrating the various parts of the immune response. Tissue macrophages are responsible for the trigger of the innate immune response to an injury by releasing pro-inflammatory [[Cytokines|cytokines]], in particular IL-1, IL-6 and TNF-α, that are responsible for the activation of the endothelium of post-capillary venules that allows neutrophils and other immune cells to adhere and extravasate (move out of the blood). With interactions with [[Mast Cells|Mast cells]] they amplify the release of vasoactive peptides including histamine and bradykinin. The cytokines IL-1, IL-6 and TNF-α along with the vasoactive peptides are responsible for the five signs of [[Inflammation - Introduction|inflammation]]:(redness ('''rubor'''), heat ('''calor'''), swelling ('''tumor'''), and pain ('''dolor'''), often accompanied by loss of function). Systemic activation of macrophages leads to the condition known as '''septic shock'''.
+Macrophages are important players in orchestrating the various parts of the immune response. Tissue macrophages are responsible for the trigger of the innate immune response to an injury by releasing pro-inflammatory [[Cytokines|cytokines]], in particular '''IL-1, IL-6 and TNF-α''', that are responsible for the activation of the endothelium of post-capillary venules that allows neutrophils and other immune cells to adhere and extravasate (move out of the blood). With interactions with [[Mast Cells|Mast cells]] they amplify the release of vasoactive peptides including histamine and bradykinin. The cytokines IL-1, IL-6 and TNF-α along with the vasoactive peptides are responsible for the five signs of [[Inflammation - Introduction|inflammation]]:(redness ('''rubor'''), heat ('''calor'''), swelling ('''tumor'''), and pain ('''dolor'''), often accompanied by loss of function). Systemic activation of macrophages leads to the condition known as '''septic shock'''.
 <p>In the latter course of inflammation, it is the blood monocytes, along with [[Dendritic Cells|dendritic cells]] that switch the immune system from innate to adaptive (see above) by interacting with CD4+ T helper cells. </p>