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Histamine
- Released by:
- -Mast cells in connective tissue
- -Basophils in blood
Increases vasodilation and permeability
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Prostaglandins
Released by every organ of the body
Intensifies the effects of histamine (increased vasodilation and permeability)
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Leukotrienes
Released by mast cells and basophils
Increases permeability
Also, functions in adherence of phagocytes to pathogens
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Cytokines
- Releases by:
- -Monocytes, macrophages
- -Lymphocytes
- -etc
- Regulates inflammatory response
- Attracts leukocytes
- Initiates fever
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Complement
Increases vasodilation and permeability
- Stimulates histamine release
- Attracts neutrophils
- Promotes phagocytosis
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Antigen
any substance recognized by the immune system
Classes-lipids, proteins, carbohydrates, and nucleic acids
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Immunogen
any substance that can evoke an immune response
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Toll-like receptors
Receptors on the surface of immune cells
-Bind to antigens found on various pathogens
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Innate Immunity: First Line of Defense
- Mechanical & Chemical Barriers
- --limit the entry, spread, and replication
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Innate Immunity: Second Line of Defense
- 1. Phagocytosis
- 2. Inflammation
- 3. Fever
- 4. Complement system (alternate pathway)
- 5. Biological Response Modifiers (BRMs)
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Neutrophils
- -short-lived
- -ingest, kill, and digest microbial pathogens
- -first to inflammatory sites
- -granules contain antimicrobial agents such as lysozymes and lactoferin (iron chelator)
- -dying neutrophils contribute to the formation of pus
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Eosinophils
mediate allergic reactions and defense against parasites (more simply, worms-helminthes)
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Basophils
- -Mast cells are tissue counterpart
- •produce cytokines in defense against parasites
- •responsible for allergic reaction
- •secrete primary (e.g., histamines) and secondary mediators (e.g.,prostaglandins & leukotrienes)
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Monocytes
-Macrophages are tissue counterpart
- •phagocytosis and intracellular killing
- •antigen presentation to T-cells
- •recruit other immune cells through cytokine production
- •Specialized macrophages: a) Kupffer cells (Liver), Glial cells (Brain), Langerhans cells (Skin), Osteoclasts (Bone), alveolar macrophages (lungs)
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Dendritic cells
- •differentiated macrophages that act as APCs to activate helper T-cells, B-cells, Cytotoxic T-cells.
- •In most organs; strategically located in mucosal tissue
- •Regulate innate and adaptive response.
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