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16 Cards in this Set
- Front
- Back
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Describe Chronic inflammation
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Persistent inflammatory response (>15 days) characterised by:
- infiltration by mononucleated cells (macrophages, lymphocytes, eosinophils, mast cells) - Tissue damage implicated by the immune system itself. - Repair by angiogenesis and fibroblast proliferation. Inflammation, Tissue damage and repair occur SIMULTANEOUSLY. |
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Causes of Chronic Inflammatory Response.
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Persistent low-toxicity microbial infection (i.e. Tripenema
Persistant exposure to low-toxicity agents (i.e. silica, lipids) Immune Disorders - Autoimmunity (auto-antigens, RE) and Delayed Hypersensitivity. |
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Mechanisms of Chronic Inflammatory Disease.
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Persistent bouts of acute inflammation.
Persistent infection. Primary Chronic Inflammation |
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Macrophages
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- Are the dominant cells in the chronic inflammatory response.
- Circulating monocytes are found in the blood (derived from haemopoetic stem cells). Half life of around 1 day. - Acute inflammation occurs. If it persists for 24-48hrs, then monocytes will migrate to the site of infection. - When they migrate into the tissues, the monocytes are differentiated into MACROPHAGES. - The macrophages are able to phagocytose. They are activated by Cytokines released from T-Cells. - Activated macrophages are much larger with an eosinophilic cytoplasm, inc conc of lysosomic enzymes - greater KILLING CAPACITY. |
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Specialised Macrophages
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- Epithelioid Histiocytes
Resemble epithelia morphology. May aggregate to form a Granuloma and this is associated with T.B. Giant Histiocytes (Giant Cells): Touton Cells - Foamy cytoplasm, central nucleus. Langerhans Cells - horse-shoe shaped ring of nuclei. Foreign-body cells - disorganised nuclei. |
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Lymphocytes.
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The next most important cell in chronic inflammation!
B Cells - Produce antibodies T Cells: CD4 - T-helper Cells, cytokines. CD8 - T-killer cells Natural Killer Cells Lymphocytes manage to sustain the activity of macrophages which would normally die after a few days. |
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If inflammation were not chronic, what might happen to macrophages?
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They die OR they are moved to the lymphatics.
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Which other cells may also be elevated during the chronic inflammatory process?
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Eosinophils
Mast Cells |
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What is a Granuloma?
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An aggregation of histiocytes, normally Epithelioid Histiocytes.
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What is the purpose of granuloma?
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Wall of the infectious agent.
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T.B is a condition which produces a granuloma. What is characteristic of a T.B granuloma?
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- Circular portion of epithelioid histiocytes
- Central caseous necrosis. - Langheran's Giant Cells in this rim. |
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What are the two types of granuloma?
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Immune Granuloma - Delayed Type 4 hypersensitivity.
Foreign-body Granuloma. |
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3 Types of Lymphocyte
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B Cells
T Cells Natural Killer Cells (which target viruses) |
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Why do granuloma form?
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The infectious agent is too large (or is too well protected) to be digested by a single macrophage.
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Distinguish between Foreign Body Granuloma and Immune Granuloma
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FB --> Tissue damage by ANY infectious agent that is too large to be removed by a single macrophage.
Immune - invasion by a micro-organism capable of eliciting a cell-mediated immune response i.e. Mycobacterium TB |
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3 Outcomes of Chronic Inflammation
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Healing by Fibrosis.
Progressive destruction of the organ (Organ Failure) Dissemintation to other organs - multi-organ failure ---> Death |
