IIT 2 Flashcards
What is the second phase of type 1 hypersensitivity?
elicitation phase
What are the steps in the elicitation phase of allergy?
- Allergen binds IgE on mast cell
- Crosslinking IgE molecules leads to mast cell degranulation
- Mediators induce immediate vasodilation, increase permeability, pruritus, bronchoconstriction
- Late phase reaction: eosinophils, lymphocytes, macrophages
What is another name for allergy?
Type 1 hypersensitivity
What is a summary of the elicitation phase of type 1 hypersensitivity?
On subsequent exposure of a sensitized individual, allergens bind and cross link IgE on the surface of mast cells. A signal transmitted to the mast cell triggers the instantaneous release of the cytoplasmic granules, spewing forth histamine and a variety of other inflammatory mediators that have immediate effects on blood vessels, causing vasodilation and increased vascular permeability, leading to redness, heat, swelling and induration.
What does histamine do in an allergic reaction?
Causes vasodilation, increased vascular permeability and bronchoconstriction.
What does serotonin do in an allergic reaction?
Present in the mast cells of cattle, causing vasodilation.
What are some key players in the chronic allergic response?
IgE, mast cells and histamine play some role in these diseases. Th2 lymphocytes, B lymphocytes and eosinophils are very important in chronic allergies.
What are some examples of type 1 hypersensitivity?
- anaphylaxis
- human: allergic rhinitis, asthma, dermatitis
- allergic skin disease: parasites, food, airborne
- Immune mediated gastroenteritis
- urticaria
- allergic bronchitis
How quickly do type 1 hypersensitivity reactions take?
Within 5-30 minutes of exposure to the antigen.
How long do type IV hypersensitivity reactions take?
They are delayed, occurring 24-72 hours after exposure to antigen, and require recruitment and activation of T lymphocytes and macrophages.
What are the two main things that happen in inflammation?
- alterations in blood vessels
- leukocytes leave blood and infiltrate tissues
What alterations in blood vessels occur during inflammation?
- dilation of arterioles to increase blood flow
- blood vessels become more permeable, plasma leaks into tissues
What alterations occur when leukocytes leave blood and infiltrate tissues during inflammation?
- transendothelial migration, chemotaxis (bind to endothelium, across vessel wall migrate to tissue and to job)
- phagocytosis, killing of pathogens, cleanup of tissues, initiation of tissue repair
What are the three phases of inflammation over time?
- serous or fibrinous effusion
- leukocyte infiltration
- repair
What are the 5 cardinal signs of inflammation?
- redness
- heat
- swelling
- pain
- loss of function
