Inflammatory Cells Flashcards
What are 5 acute inflammation effector cells?
- vascular endothelial cells
- neutrophils
- mast cells/basophils
- eosinophils
- monocytes/macrophages
Vascular endothelial cells
Inflammation
- contraction
- release of chemical mediators (NO)
- expression of adhesion molecules and receptors
Leukocytes
- neutrophils
- eosinophil
- basophil/mast cell
- monocyte/macrophage
- lymphocyte/plasma cell
What is the avian equivalent of a neutrophil?
Heterophil
Neutrophil cell characteristics
Segmented nucleus, multiple complex granules
- recruited by IL-8!!
- short lived –> 24 hrs in circulation, 1-2 days in tissue
- aka: polymorphonuclear leukocytes
Neutrophil function
Innate immunity to bacteria and fungi
- phagocytosis
- release of granular contents
What are the 3 phases of neutrophil phagocytosis?
- attachment to particles to the cell surface
- ingestion of particles
- breakdown of particles
_______ greatly facilitates phagocytosis
Opsonization
- via IgG antibodies and complement
Neutrophil granules
- myeloperoxidase: converts H2O to hypochlorous acid which is toxic to microbes
- lysozyme
- antimicrobial substances
- gelatinase: break dwon tissue
Enzymes released cause _____ of the exudate and accumulation of pus
Liquefaction
- **reptiles and birds have reduced concentration of enzymes and cannot liquefy the exudate, leading to formation of caseous material
Neutrophil extracellular traps
Extracellular fibrillary networks that provide high concentrations of antimicrobial substances
- trap microbes to prevent spread
- meshwork of nuclear chromatin that binds and concentrates antimicrobial peptides and enzymes
Neutrophil production and maturation takes place in the _______
Bone marrow
- cytokines stimulate endothelial cells and fibroblasts to produce colony stimulating factors —> CSFs act directly on hematopoietic subpopulations in bone marrow to increase cellular proliferation/differentiation –> release from bone marrow is orderly and age-related with mature segmented cells released first
Eosinophils
1-5% of WBCs
- short lived –> 12 hrs in circulation, 1 week in tissue
- emigrate from blood and live in subepithelial sites in skin, lung, GIT, and endometrium
- enter lesions during transition from acute to chronic inflammation!!!
What attracts eosinophils?
Histamine, eosinophil chemoattractant factor A (mast cells), eotaxin
Eosinophil function
- innate immunity to parasites
- associated with allergies to hypersensitivity
- modulate local immune responses = production and release of cytokines
Eosinophil cell characteristics
- bilobed nucleus
- cytoplasmic granules
- major basic protein, lysosomal enzymes and peroxidases (less effective than neutrophils)
- result in major tissue damage (collagenolysis)
Eosinophilic exudate
Chronic
- green tinge to muscle
Mast cells/basophils
Found in all supporting tissues
- distributed in skin, GIT, and blood vessels (rapid response)
- long lived (4-12 weeks)
- replicate in tissue!!
- deeply basophilic granules and condensed nucleus
Metachromatic granules of mast cells
- histamine
- eosinophil chemotactic factor
- heparin
- synthesize prostaglandins, leukotrienes and PAF
- proteolytic enzymes (tryptase)
Mast cells express high affinity receptors for ______ on suface
IgE
- stimulated by cross linking of IgE
- fusion of cytoplasmic granules which then fuse with the plasma membrane and exit thru a pore
- immune system must be primed!!!
Immediate response of mast cell degranulation
- vasodilation
- vascular leakage
- smooth muscle spasm
Late phase reaction of mast cell degranulation
- leukocyte infiltration
- epithelial damage
- bronchospasm
Monocytes and macrophages
Originate in bone marrow, migrate in blood for 6 days and settle in tissues as macrophages
- monocytes are short lived in circulation
- macrophages are long lived in tissues, retain ability to proliferate
Monocyte/macrophage function
- phagocytosis
- antigen presentation
- immune modulation
Monocyte cell characteristics
Large nucleus with indentation, multiple granules and vacuoles
- granules are similar to primary neutrophilic granules
What are the 2 types of macrophages?
- those that reside within a specific tissue (physiologic)
- those derived from monocytes in response to a stimulus
Tissue macrophages
- kupffer cells (liver)
- microglia (CNS)
- alveolar macrophages (lung)
- langerhans cells (skin)
- osteoclasts (bone)
Macrophages recruited to inflammation
Respond by chemotaxis
- arrive as a second wave after neutrophils (12-48 hrs) take over
- antigen processing and presentation
- engulf and destroy tissue debris and foreign material (less efficient than neutrophils)
- modulate immune response via release of cytokines!!
How do macrophages destroy tissue and foreign material?
- release of lysosomal enzymes
- free radicals
- opsonization enhances phagocytosis
______ are one of the main triggers of the adaptive immune response
Macrophages
Platelets
Biconvex discs
- arise from megakaryocyte fragmentation in marrow
- hemostasis control
- deliver inflammatory mediators to injured sites
- preformed substances in granules (histamine)
- chemokines involved in chemotaxis (platelet activating factor)
- thromboxane A2 (vasoconstriction)
- growth factors
