Topic 10: Eosinophil granulocytes, mononuclear phagocytes, thrombocytes Flashcards

1
Q

What should be mentioned in this topic?

A
  • Eosinophil Granulocyte
  • Chemotaxis
  • Antiallergic Effect
  • Mononuclear Phagocyte
  • Antigen Presentation
  • Thrombocyte s /Plate le ts
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2
Q

Eosinophil Granulocyte

A
  • Cells with diameter of 12-14micrometer.
  • Nucleus is less segmented, red coloured granules are seen in the cytoplasm.
  • These granules are actually lysosomes, containing enzymes. In horses the granules appear big,
    light and often covering the nucleus.

-Their proportion in the blood increases during allergic processes.

  • Lifetime:
  • Circulation 3-8hrs
  • Tissues 3-5 days
  • Stronger chemotaxic sensitivity.
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3
Q

Chemotaxis

A
  • WBC migrate towards higher concentration of specific signals.

Most important chemicals:

  • Products of tissue breakdown
  • Histamine
  • Complement factors
  • Broken polysaccharide capsule of bacteria
  • Chemotaxines produced by WBCs
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4
Q

Antiallergic Effect

A
  • phagocytosis and form “respiratory burst”, but to a lesser degree than neutrophil granulocytes.
  • Clears away metabolites produced by the basophil cells provoking inflammation and
    assure the cellular elimination in parasites.
  • Gather in inflammatory areas by chemotaxis.
  • The cell takes up and breaks down both the histamine produced by the basophil cells and the SRS-A that maintains inflammation for a long time.
  • Able to degranulate. The most effective substances against parasites are the alcalic proteins
    produced by these cells.
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5
Q

Mononuclear Phagocyte

A
  • Biggest WBC 15-25micrometers.
  • Big non segmented nucleus which is bean shaped.
  • Cytoplasm contains asurophil granules where the degrading enzymes for the phagocytosed
    elements can be found.
  • During the antigen-eliminatory processes the monocytes “present” the antigen to the other
    cells of the immune system.

-The secretory function is very important.
- Besides the intracellular digesting enzymes they produce extracellular enzymes, interleukin-1,
interferons and prostaglandins.

Lifetime:

  • In circulation: 10-40hours
  • In tissues: 2-3 months

Migration and Chemotaxis:

  • Similar to neutrophil granulocytes
  • Circulating fraction is really small
    • Extravasal supply: tissue macrophages of significant importance.
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6
Q

Antigen Presentation

A
  • APC cells manage to express the digested pieces of the phagocytised antigen together with their own MHC to the cell surface.
  • The adequate receptor of the helper T-lymphocyte (Th) recognises the piece of the antigen and the MHC complex. This initiates the immune system and finally leads to antibody production.
  • This occurrence is called the antigen presentation.
  • Infected somatic cells manage to express foreign material to the cell surface too. This goes together with the MHC-I type surface marker. If MHCI plus an antigen complex occurs on the surface of the cell, it will be recognised by the cytotoxic T-lymphocyte receptors and the infected cell will be destroyed.
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7
Q

Mononuclear Phagocyte:

Enzymes in Granules:

A
  • Proteases
  • Myeloperoxidase
  • Superoxid dismutase
  • Acidic and alcalic phosphatise
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8
Q

Mononuclear Phagocyte:

Secretion of monocytes:

A
  • loosening tissues with enzymes:
    • collagenase
    • elastase
    • angiotensine convertase
  • Stimulation of immune response:
    • interleukin-1
    • Interferon
    • prostaglandins
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9
Q

Thrombocytes/Platelets

A
  • 1.5-3.5micrometers
  • Lifetime: 5-10days
  • Passive movement
  • Found mainly in the circulation
  • No nucleus, granular cytoplasm
    • Delta granules: calcium, serotonin and ADP
    • Alpha granules: coagulation factors
  • Originate from a megacaryocyte
  • Plasma membrane contain invaginations that form canaliculi systems
  • Thrombocyte activating factors prompt the release of granules
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10
Q

Enzymes in the Eosinophil granulocytes:

A

Enzymes:

  • Histaminase,
  • Aril-sulfatase,
  • Myeloperoxidase,
  • Acidic and alcalic phosphatise,
  • Nuclease
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11
Q

Explain the mononuclear phaocyte systems:

A

MPS: Mononuclear Phagocyte System. MS: Macrophage system

  • RES: Reticulo endothelial system
  • RHS: Reticulo histiocytic system
  • Task: Antigen presentation, Secretion
  • Cells with dividing capacity
  • Form polynuclear giant cells which has increased phagocytosis
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