Hypersensitivity Flashcards
Define pathogen
A bacterium, virus or other microorganism that can cause a disease
Allergic reactions are also called
hypersensitivity reactions
how many categories of hypersensitivity reactions are there
Four (type I-IV)
What is type I hypersensitivity
IgE mediated: Allergic Reaction
Once exposed to an allergen which cells are bound with IgE molecules
Mast Cells
basophils
eosinophils
The binding of IgE molecules by the mast, basophils and eosinophils is called
sensitization
When exposed again to an allergen after sensitization, what is relieased
inflammatory mediators
what are the inflammatory mediators
histamine
leukotrines
prostaglandins
what do the inflammatory mediators do
result in vasodilation, bronchial smooth muscle constriction and mucus production
Type one reactions can be either
local or systemic
Type II hypersensitivity is what kind of reaction
a tissue-specific reaction
Why do type II hypersensitivities occur
a result of haptens that cause IgG or IgM antibodies to start a response
What are haptens
small molecules that cause an immune response when it attaches to a protein
Who are the primary effectors of type II responses
macrophages
After IgG or IgM antibodies bind to the antigen what can happen
- Cellular destruction through phagocytosis by macrophages
- Damage to cells by neutrophils triggering phagocytosis
- Natural killer cells to release toxic substances that destroy the target cell
- Malfunction of the cell without destruction
Biggest difference between type II and type III responses
in a Type II response, the antibody binds to the antigen on the cell surface, but in Type III responses, the antibody binds to the antigen in the blood or body fluids and then circulates to the tissue.
Primary effector cell in type III responses
neutrophils
