Topic 9: Neutrophil and Basophil granulocytes Flashcards
What should be mentioned in this topic?
- Basics about WBC
- Neutrophil Granulocyte
- Migration
- Phagocytosis
- Basophil Granulocyte
- Degranulation
- Specific Way of Degranulation
- Nonspecific Way of Degranulation
Basics about WBC
- White blood cells are elements of the organism’s immune system.
- they develop in the bone marrow (Except for the lymphocytes)
- Its physiological amount in mammals is 5-15x109/L and in birds is 20-30x109/L.
- Factors effecting amount: species, age, sex, time of the day.
- Neutrophilic type: horses and carnivores 30% agranulocytes, 60% granulocytes
- Lymphocytic type: ruminant, swine, bird, 60% agranulocytes, 30% granulocytes
Neutrophil Granulocyte
- Diameter 10-14 micrometer.
- Strongly segmented nucleus having small, purple-red-coloured granules in the cytoplasm.
- 80% neutrophil granules and 20% by bigger, asurophil granules.
- Most important elements of the cellular immunity: proceed a very effective phagocytosis, they don’t need previous meeting with the foreign body for its recognition and elimination, display their effect immediately.
- PMN Cells: Polymorphonuclear cells
- Lifetime: 6-7 hours in circulation, Tissue: 2-3 days
- Mobilisation: Leukocytosis.
- Clinically important:
Different values in case of infection.
Neutrophil Granulocyte
Migration
-Neutrophils are able to actively move/migrate.
Movement is based on building up and dissociation of actin chains. As a result of actin polymerisation actin fibers are continuously formed in the cell.
Types: Contractile actinbundles, gel-forming, actin-bundles or tightly united actin-bundles can be formed. Migration by philopodium
Neutrophil Granulocyte
Phagocytosis
Neutrophil granulocytes are not only able to take up bigger particles but also able to engulf molecules. As an example for phagocytosis we show LDL uptake:
- External part of LDL receptor binds an LDL
- Affected by this, the internal clathrin binding site activates and a clathrin coated pit is formed, that finally ends up with endocytosis and forming of a clathrin coated vesicle
- Calthrin: A complex consisting of three small and three bigger peptides that is inherited
conservatively during evolution. - If specific factors and non specific factors bind a foreign body, the phagocyting ability of neutrophil granulocytes increases to a hundred times higher level.
Opsonisation: There are some natural substances in the blood plasma that can bind foreign antigens similarly to immunoglobulins. They bind with the neutrophil granulocytes and significantly stimulate phagocytosis.
Immune Adherence – The specific immunoglobulin able to bind the antigen is present already and binds the antigen. Results: Increased phagocytosis. The cell expresses the Fc receptors on the surface again making additional phagocytosis possible.
Basophil Granulocyte
Rarest WBC
- Diameter 9-10micrometers
- Slightly granular nucleus bent in a horse shoe or an S-like manner.
- Granules contain histamine, serotonin and heparin besides the enzymes; Hyaluronidase, protease, myeloperoxidase.
- Moving capability is low.
- Main task: help the immune reactions: They loosen the tissues where the antigens
are present so the other defence elements can more easily get to the place of infection. - No phagocytosis, almost no endocytosis
- Extravasal fraction: Mast cells can be found in the tissues
- These cells loosen the tissues
- Stimulate the elimination of antigens
Basophil Granulocyte:
De granulation
- The basophil granulocytes bind IgE type antibodies on their surface.
- In case an antigen binds to the IgE, the cell quickly releases its enzyme-supply to the environment: degranulation occurs.
- The released enzymes loosen the environment and give space to additional immune processes.
- Extreme degranulation ends up with pathological damage in the organism’s own tissues: allergy
- Degranulation is stimulated by many different ways of the immune system
Basophil Granulocyte:
Specific Way of Degranulation
- on surface of the basophil granulocytes there are receptors that bind the Fc part of the IgE- type immunoglobulins
- The IgE that was produced earlier against another antigen can still bind to the above mentioned receptor if the IgE did not bind the antigen yet.
- The basophil cell “equipped” with IgE roams in the insterstice. In case of meeting an antigen, it binds it.
- The binding itself evokes the vacation of the basophil cell granules. The released materials loosen the tissues. The tissue infected by the antigens becomes accessible for the other cells of the immune apparatus.
Basophil Granulocyte:
Nonspecific Way of Degranulation
- Basophil cells cause inflammation
- When an antigen is detected they emit a large amount of a certain material to the
plasma and the interstitial space that loosens the tissues. This makes it much easier
for the immune cells and antibodies to get to the antigen..
- When an antigen is detected they emit a large amount of a certain material to the
- The degranulation is stimulated by the C3a and C3b complement factors. The receptor
specific for these factors is expressed to the surface of the cell again and again. - Additional products of the degranulation are the heparin (prevents coagulation therefore accelerates the process of the antibodies getting into the interstitium) and the slow reacting
factor of anaphylaxis (SRS-A). - This SRS-A causes long lasting inflammation.
- The released histamine and hyaluronidase loosen the tissues so the immune cells and molecules can get to the antigens. Heparin helps by preventing coagulation.
Explain Leukocytosis and Leukopenia:
- Increased, leukocytosis, in the number of the white blood cells can be caused in the first place
by bacterial, viral and parasitic infections, also by inflammatory processes. - Decrease, leukopenia, can be a result of radioactive radiation, mushroom-toxins or some
medications.
Granula of neutrophil granulocytes contain enzymes:
– lysosyme – myeloperoxidase – superoxid dismutase – acidic, alkalic phosphatase – nuclease – protease
Form of the neutrophil cells according to age:
- Young forms in the quality blood count: o Stab form (stick shaped)
- Jugend form (bean shaped)
- Matured neutrophil (3-5 segments)
- Over matured neutrophil (5-10 segments)
What does it mean when we say that the neutrophil cells “Shift to the left or right”?
- “Shift to the left” in the blood count: Forced hematopoiesis, presence of fresh (acute)
infection - “Shift to the right” in the blood count: Presence of aged neutrophil granulocytes, incomplete
hematopoiesis.
Steps of phagocytosis:
Binding Participants: – phagocyte – cell/receptor – lysosome – nucleus – actin cortex – foreign body – binding place on the foreign body's surface
