Block III: video 4 Flashcards
What are the histological characteristic of mast cell?
- A large cell with round nucleus
- Contains large granules in the cytoplasm – which stain with eosin in H&E of plastic embedded tissue
- Shows metachromatic staining of the granules with toludine blue
- Contains large dense staining granules in EM
identify
Mast cells stained with H&E in plastic embedded sections
identify
Mast cells stained with H&E in plastic embedded sections
identify
Light micrograph of mast cell
stained with toluidine blue
identify
EM of mast cell
Where is mast cell prominent?
immune system
What are the types of immunological reactions of mast cells?
- Hypersensitivity reactions in which the immune system activation over-reacts often resulting in immune system action which may be
detrimental to the body (This can be either humoral immediate hypersensitivity reactions within minutes or delayed cytotoxic reactions) - Adaptive immune system: this normally requires a longer time for
response and requires the synthesis of immunoglobulin antibodies or the production of cytotoxic t-lymphocytes
What is Type I hypersensitivity?
Mast cells may be involved in Type I hypersensitivity reactions which
depend upon the binding of immunoglobulin E (IgE) to the plasma
membrane of the cell prior to the hypersensitivity reaction
What are some functions of the mast cell?
- function involves pharmacological actions of the substances released from its granules, cytoplasm, and membranes.
- involved in immediate hypersensitivity Type I immune reactions
What does the granules in mast cells contain?
- histamine
- eosinophile chemotactic factor
- neutrophil chemotactic factor
- neutral proteases
- heparin
What does histamine do?
potent vasodialator and causes
contraction of smooth muscle in airways (edema)
What does eosinophile chemotactic factor do?
attracts eosinophils into area as part of the inflammatory process
What does neutrophil chemotactic factor do?
attracts neutrophils into area
What does neutral proteases do?
(serine proteases) = generate
angiotensin II in response to vascular tissue injury and may induce apoptosis in damaged vascular
smooth muscle cells (tryptase and Chymase)
what does heparin do?
may act to condense the contents; interacts with platelets (highly negative)
By what does the degranulation of the mast cell happen?
is brought about typically by binding of antigen to IgE molecules which are bound to the surface of the mast cell. Can also involve complement related binding
WHat happens in response to 1st contact with allergen?
the immune system will produce large amounts of IgE which will become bound to the surface of
the mast cell (and basophil)
WHat happens in response to 2nd exposure to the allergen?
crosslinking of as few as 2 of the IgE molecules on the surface can lead to degranulation of the cell and release of the contents of the granules
identify
EM of mast cell undergoing degranulation
WHat other stuff does the mast cell release?
additional secondary mediators including prostaglandin D2, bradykinins, thromboxin A2 and leukotrienes from membrane lipid as
important mediators of vasodialation, vasoconstriction, and bronchiospams