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
What are leukotrienes?
(similar action to histamine, but slower action) are also released from
the plasma membrane upon degranulation causing bronchospasms.
Leukotrienes are resistant to antihistamines and thus anti-histamine therapy will not entirely
relieve allergenic responses
What are some CC involving mast cell degranulation?
- hay fever
- asthma
- anaphylactic shock
What is hay fever?
edema of nasal mucosa due to release of histamine
What is asthma?
bronchiospasms due to leukotriene and histamine effects on smooth muscle in lungs
What is anaphylactic shock?
results from a large loss of fluids from vascular system due to effects of histamine and leukotrienes leading to vascular collapse. Effects occur in 1 -3 minutes after contact with allergen.
Immediate treatment with vasoconstrictors like epinephrine is required or death can occur
What are some histological characteristics of macrophage?
- large cell with lightly basophilic cytoplasm
- plasma membrane highly folded with numerous projections
- nucleus often indented or kidney shaped
- numerous lysosomes
When is the macrophage most easily recognized?
when has phagocytosed debris
Where is macrophage derived from?
derived from monocytes in blood
that enter CT
WHat is the macrophage member or?
mononuclear phagocyte system
identify
EM of macrophage
identify
lung, alveolar macrophage
identify
Macrophages (black) filled with phagocytosed dye
What are some functions of the macrophage?
- phagocytosis of microbes, particulate material, and antigen-antibody complexes.
- secretion of a variety of immunologically important molecules including interleukin I (lymphocyte mitogenic factor) and interferon (antiviral)
What do macrophages have on their plasma membrane?
major histocompatibility complex
II.
What is major histocompatibility complex II?
Antigenic fragments from the phagocytosed structures such as
bacteria broken down by the macrophage become bound to the major histocompatibility complex II which is transported to the plasma
membrane where the antigenic fragments can be presented to
lymphocytes to trigger immune reactions
What are the two types of macrophages and their fucntions?
- Classically activated macrophages (M1 macrophages), occur early in the inflammatory process and have the capacity, through the production of nitric oxide (NO) and other intermediates, to destroy microorganisms at the site of inflammation.
- Alternatively activated macrophages (M2 macrophages)- Occur later in areas of inflammation and in general are anti-inflammatory
and work toward resolution of inflammation and promote rebuilding of extra-cellular matrix, cell proliferation, and angiogenesis. (repair)
What are foreign body giant cells?
When stimulated macrophages may fuse to give giant multinucleated cells known as foreign body giant cells in order to either surround and wall-off large foreign objects or to phagocytose large particles.
These foreign body giant cells allow macrophages to wall-off from the body clusters of bacteria or parasites that can not be handled by a single macrophage. In this process the
macrophages can form large masses of cells known as granulomas
In addition, these foreign body giant cells can be clinically important at
the surface of biopolymer implants , stents, pins and other surgical
implants where they may attempt to destroy the implants
What is Matrix metalloproteinases?
family of proteins known as the matrix
metalloproteinases (MMPs) which are zinc-associated proteinases.They are particularly prominent in their ability to degrade collagen.
play an important role of remodeling of connective tissue both under normal and pathological conditions.
In addition, expression of the metalloproteinases has been linked to the ability of cancer cells such as endometrial cancer cells to metastasize.
What are plasma cells derived from?
antigenically
stimulated B-lymphocytes
How is the pattern of plasma cells called?
round nucleus with clockface
chromatin pattern; due to heterochromatin
What organelle is visible adjacent in plasma cells?
juxta-nuclear Golgi - negative
staining in LM
how is the staining in plasma cells?
basophilic translucent (nongranular)
cytoplasm
WHat is the function of plasma cells?
Is the synthesis of antibodies
(immunoglobulins)
identify
Plasma cells (arrows) in lamina propria of intestine; negative golgi can be seen
identify
EM of plasma cell
What is reticular CT?
specialized connective tissue of
lymphoid and blood-forming
(hemopoietic) organs such as
bone marrow, spleen, tonsils,
lymph nodes
by what are reticular fibers formed?
in reticular CT made by a specialized cell called a reticular cell
How is the gorund substance in reticular CT?
ground substance = blood plasma or
lymph. NO GAGS
What is the function of reticular CT?
Provides a CT supporting stroma
that allows easy movement of fluid
and cells through organ
How deos cell in reticular CT aid?
cell wraps around fibers and
maintains them; similar to fibroblast
