Mast cell histology and its visualization methods - maha hammady

Mast cell histology and its visualization methods maha hammady

1. Mast cell Histology and its Visualization Methods Maha Hammady Hemdan MBBCh , Demonstrator at Medical Histology & Cell Biology Department, Faculty of Medicine Alexandria university

2. Mast cells arise from bone marrow stem cells and function in mediating the inflammatory process and immediate hypersensitivity reactions. Mast cells, among the largest of the fixed cells of the connective tissue, are 20 to 30 μm in diameter. They are ovoid and possess a centrally placed, spherical nucleus, The presence of numerous granules in the cytoplasm is the identifying characteristic of mast cells

3. Content of Mast cell granules: Secondary (or newly synthesized) mediators: Preformed mediators (primary mediators): leukotrienes (C 4 , D 4 , and E 4 ): increase vascular permeability and cause bronchiospasms Heparin: 2. Heparin is a sulfated GAG that is an anticoagulant thromboxanes (TXA 2 and TXB 2 ) : Thromboxane A 2 is a vigorous platelet-aggregating mediator Histamine causes vasodilatation and increases the vascular permeability platelet-activating factor (PAF) : causes greater vascular permeability. Complement components leak out of blood vessels and are cleaved by neutral proteases to form additional agents of inflammation bradykinins , interleukins (IL-4, IL-5, IL-6) : is a powerful vascular dilator that causes vascular permeability Eosinophil chemotactic factor attracts eosinophils to the site of inflammation. tumor necrosis factor-alpha (TNF-α): It increases expression of adhesion molecules in endothelial cells and has antitumor effects Neutrophil chemotactic factor attracts neutrophils to the site of inflammation

4. Mast Cell Development: Because basophils and mast cells share some characteristics, it was once believed that mast cells were basophils that had left the bloodstream to perform their tasks in the connective tissues. It is now known that basophils and mast cells are different cells and have different precursors .

5. Mast Cell Development: Mast cell precursors probably originate in the bone marrow, circulate in the blood for a short time, and then enter the connective tissues, where they differentiate into mast cells and acquire their characteristic cytoplasmic granules.

6. Distribution : Mast cells are located throughout the body They are classified according to their location into: 1- the connective tissue type: where they are concentrated along small blood vessels . They contain mostly heparin in their granules. These cells also contain granule-associated tryptase and chymase and are referred to as MC TC mast cells or connective tissue mast cells 2-Mucosal mast cells: They are present in the subepithelial connective tissue of the respiratory and digestive systems. Mucosal mast cells contain chondroitin sulfate instead of heparin. Mucosal mast cells contain chondroitin sulfate instead of heparin and produce only tryptase and are termed MC T mast cells or mucosal mast cells . The reason for the existence of the two diverse populations of mast cells is not understood

7. Visulaization : 1-By Light Microscope: A:Metachromatic dyes: The presence of numerous granules in the cytoplasm is the identifying characteristic of mast cells. These membrane-bound granules range in size from 0.3 to 0.8 μm . Because they contain heparin (or chondroitin sulfate , these granules stain metachromatically with toluidine blue (i.e., toluidine blue stains the granules purple)

8. Visulaization : 1-By Light Microscope: A:Metachromatic dyes: Metachormasia indicate that the structure being dyed assumed a color different from that of the dye itself. Metachromasia is due to the presence of tissue polyanions that induce a polymerization of dye molecules . The process involves a shift in the absorption spectrum of the dye towards shorter wave-lengths

9. Visulaization : 1-By Light Microscope: A:Metachromatic dyes: Metachromatic staining is important in the detection of mast cells and is strongly recommended as a routine stain for this purpose. section of rat peritoneal mast cells stained with toluidine blue. Numerous cytoplasmic metachromatic granules are recognizable

10. Visulaization : 1-By Light Microscope: B- Histochemical method Among the histochemical methods for staining mast cells worth mentioning are Sudan Black B (to diagnose mast cell leukemia )

11. Mast Cell Leukemia and Other Mast Cell Neoplasms Mastocytosis represents a spectrum of disorders characterized by mast cell hyperplasia. Neoplastic mast cell disorders have recently been apportioned into 6 categories by the World Health Organization (WHO).These disorders may be reactive or neoplastic , and they range from benign syndromes with cutaneous involvement to malignant variants with mast cell infiltration of multiple organs, including the bone marrow. Approximately 15% of patients with malignant mastocytosis develop mast cell leukemia, a very rare variant of acute myeloid leukemia Typical granular staining with Sudan Black B of a blast and a neutrophil from a patient with FAB M1 acute myeloid leukemia. Visulaization : 1-By Light Microscope: B- Histochemical method

12. [Mast cell leukemia--case report] A 72-year old female was admitted to hospital. She had eccematoid changes on her trunk and underarms. Radiogramm showed osteolytic lesions of the right thigh and pelvis. FNA of the bone marrow revealed hypercellular smear with 80% of mast cells and immature mast cells which were cytochemically positive to toluidine , alcian blue, acid fosphatase and Sudan black and negative to periodic acid Schiff (PAS) and peroxidase . The peripheral blood smear showed single mast cells which were positive to toluidine . The bone marrow biopsy confirmed mast cell leukemia. Two month after the diagnosis the patient suffered from right thigh fracture and was treated with local radiotherapy, antihistaminic and analgetic therapy. The patient died within 6 month after the diagnosis. https://sci-hub.se/https://www.ncbi.nlm.nih.gov/pubmed/24279257 Visulaization : 1-By Light Microscope: B- Histochemical method

13. CTMCs could be distinguished from MMCs by red staining with safranin due to the presence of large amounts of heparin in their secretory granules CTMCs contain heparin that is lacking in MMCs. Conversely, MMCs express chondroitin sulfates A and B, which are not found in CTMCs After appropriate fixation and sequential staining with Alcian blue and safranin , MMCs stain blue, being thus differentiated from CTMCs which stain with safranin and are red. Visulaization : 1-By Light Microscope: C- Alcian Blue- Safranin

14. CTMCs could be distinguished from MMCs by red staining with safranin due to the presence of large amounts of heparin in their secretory granules CTMCs contain heparin that is lacking in MMCs. Conversely, MMCs express chondroitin sulfates A and B, which are not found in CTMCs After appropriate fixation and sequential staining with Alcian blue and safranin , MMCs stain blue, being thus differentiated from CTMCs which stain with safranin and are red. Visulaization : 1-By Light Microscope: C- Alcian Blue- Safranin Alcian blue- safranin stained brain mast cells, Red and blue-stained mast cells, solid arrow indicates blue mast cells (b), Red-stained mast cell (c), blue-stained mast cells (d),

15. Visulaization : 1-By Light Microscope: D- immunohistochemisty : anti- Tryptase and anti- Chymase Mast cells from different anatomical sites contain different profiles of these enzymes as well as of other proteases. Immunohistochemical analysis of paraffin-embedded, formalin-fixed Human colon tissue, labelling Mast Cell Tryptase using ab134931 at a 1/500 dilution.

16. Visulaization : 1-By Light Microscope: D- immunohistochemisty : anti- Tryptase and anti- Chymase Mast cells from different anatomical sites contain different profiles of these enzymes as well as of other proteases. Immunohistochemical analysis of paraffin-embedded, formalin-fixed Human tonsil tissue, labelling Mast Cell Tryptase using ab134931 at a 1/500 dilution

17. Visulaization : 1-By Light Microscope: D- immunohistochemisty : anti- Tryptase and anti- Chymase Mast cells from different anatomical sites contain different profiles of these enzymes as well as of other proteases. Formalin fixed paraffin embedded human tonsil stained with Mast Cell Chymase antibody (Mob 346).

18. Visulaization : 2-By Electron Microscope: EM reveals differences in size and form and display variations in ultra-structure even within the same cell. Otherwise, the cytoplasm is unremarkable; it contains several mitochondria, a sparse number of RER profiles, and a relatively small Golgi complex. The cell surface contains numerous microvilli and folds