L2a_Phagocytes, Mast Cells, Basophils and Eosinophils.pptx

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1. Phagocytes , Mast cells, Basophils and Eosinophils

2. Blood Cells

3. Phagocytes (including neutrophils and macrophages Primary function: ingest and destroy microbes and get rid of damaged tissues. (process: phagocytosis) process of uptake of microbes and particles followed by digestion and destruction of this material 1 litre of blood = about 6 billion phagocytes Important in : Fighting infections Getting rid of dead and drying cells

4. Phagocyte Monocyte Macrophages Neutrophils Dendritic cells Mast cell Have receptors on their surfaces which can detect harmful agents Eg . bacteria Mechanism: Recruitment of cells to sites of infection. Recognition of and activation by microbes. Ingestion of microbes (phagocytosis). Destruction of ingested microbes.

5. Phagocyte Monocyte A type of white blood cell (or leukocyte ) Types of white blood cell ( leukocyte ) Neutrophils Monocyte Basophils Lymphocytes Mast cell Phagocytic

6. Phagocyte Monocyte A type of white blood cell (or leukocyte) Largest type of leukocyte (3-8%) A mononuclear leukocyte Can differentiate into macrophages or dendritic cells Appearance : Amoeboid Have granulated cytoplasm Containing unilobar nuclei, nucleus is ellipsoidal (kidney/bean-shaped)

7. Phagocyte Monocyte Produced in bone marrow (from precursors – called monoblast ) Circulate in bloodstream for about 2 – 3 days then move into tissues throughout the body Half of them are stored in spleen Monocyte which migrate from bloodstream to tissues: Will differentiate into tissue resident macrophages or dendritic cells

8. Phagocyte Monocyte Monocyte and their macrophage and dendritic cell progeny serves 3 main functions in immune system: Phagocytosis Antigen presentation Cytokine production Monocyte itself is capable to: Perform phagocytosis Kill infected host cells Cytokine -category of small proteins that are important in cell signalling Eg . interferon, interleukin, and growth factors

9. FIGURE 2-2 Maturation of mononuclear phagocytes. Tissue resident macrophages, which differentiate into specialized forms in particular organs, are derived from precursors in the yolk sac and fetal liver during fetal life. Monocytes arise from a precursor cell of the myeloid lineage in the bone marrow, circulate in the blood, and are recruited into tissues in inflammatory reactions, where they further mature into macrophages. Subsets of blood monocytes exist, which have distinct inflammatory or reparative functions (not shown).

10. MACROPHAGES Formed in response to an infection/damaged/dead cell specialized to recognize, engulf and destroy target cell Formed from differentiation of monocyte. Type : long-term immunity (presents microbe's antigen to its surface to alert other WBC to multiple the immune response) tissue damaged/infected monocyte leave blood stream and enter affected tissue/organ monocyte undergo series change to form macrophages macrophage form many structure in order to fight different microbes. macrophages provide first line defense in protection of host

11. NEUTROPHILS known as neutrophil granulocyte/ neutrocyte have tiny granule full of enzyme and peptide which chop bacteria after taken them in vacuole via phagocytosis process Function Destroy bacteria and other parasite during infection Essential for process proteolysis, which water is added to bond that make up protein – can be broken down into smaller substances

12. FIGURE 2-1 Morphology of neutrophils, mast cells, basophils, and eosinophils . A , The light micrograph of a Wright- Giemsa –stained blood neutrophil shows the multilobed nucleus, because of which these cells are also called polymorphonuclear leukocytes, and the faint cytoplasmic granules. B , The light micrograph of a Wright- Giemsa –stained section of skin shows a mast cell (arrow) adjacent to a small blood vessel, identifiable by the red blood cell in the lumen. The cytoplasmic granules in the mast cell, which are stained purple, are filled with histamine and other mediators that act on adjacent blood vessels to promote increased blood flow and delivery of plasma proteins and leukocytes into the tissue. C , The light micrograph of a Wright- Giemsa –stained blood basophil shows the characteristic blue-staining cytoplasmic granules. D , The light micrograph of a Wright- Giemsa –stained blood eosinophil shows the characteristic segmented nucleus and red staining of the cytoplasmic granules.

13. Mast Cells

14. Morphology Known as PMN granulocytes . PMN means polymorphonuclear . Have cytoplasmic granules. Granules contains inflammatory mediators such as histamines . Have high affinity plasma membrane receptors for IgE . Usually coated with IgE

15. Where are mast cells come from? Where are they located? Mast cells derived from bone marrow Cytokine stem cell factor (c-Kit ligand) is essential for the mast cell development Located in tissues, adjacent to small blood vessels and nerves Present in the skin and mucosal epithelia

16. What are the functions of mast cells? Involves in innate and adaptive immune response It produces cytokine which kept in granules, the cytokine is histamine As sentinels in tissues, recognise foreign particles and respond When the antibodies on the surface of mast cells bind the antigen, a series of signalling event are induced Those signalling event lead to release of histamines into extracellular space Histamine promotes blood flow in blood vessels, causing inflammation

17. Other functions of mast cells Provide defence against helminths (parasitic worm) Responsible in allergic reaction when the mast cell is too sensitive to antigen, it over react Mast cell disorders: a) Mastocytosis – Presence of too many mast cells in body b) Mast cell activation syndrome (MCAS) – Normal number of mast cells are too easily activated, excessively release chemical mediators

18. Basophils Type of white blood cells Represent 1% of white blood cells Granulocytic – active in inflammatory responses Oversensitive basophils cause the allergic reaction Release Histamine and Heparin(anticoagulant) Can perform phagocytosis

19. EOSINOPHILS

20. Eosinophils Specialized cell of the immune system Has nucleus with two lobes ( Bilobed ) Cytoplasm filled with approximately 200 large granules containing enzymes and proteins These enzymes are harmful to the cell walls of parasites but can also damage host tissue Granules also contain basic proteins that bind acidic dyes such as eosin Eosinophils are usually present in peripheral tissues, especially in mucosal linings of the respiratory, gastrointestinal, and genitourinary tracts

21. Eosinophil Maturation Bone-marrow derived Cytokines Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF), Interleukin 3 (IL-3) and Interleukin 5 (IL-5) promote maturation from myeloid precursors Spend 8 days in the process of maturation before moving into the blood vessels Travel through the vessels 8-12 hours before arriving at their destination tissues where they can remain for 1-2 weeks

22. Conclusion Human immune system is extremely complex Does not rely on one single mechanism to deter invaders but uses many strategies Phagocytes – provide innate immunity (Neutrophils & Macrophages) Mast cells, Basophils and Eosinophils - additional cells that play roles in innate and adaptive immune responses