Hypersensitivity Flashcards
(19 cards)
what is hypersensitivity?
excessive/inappropriate activation of immune response
which type of reaction involves the classic allergic rxns, is IgE mediated and has a fast onset?
Type 1
What are the manifestations of Type 1?
swelling, redness, anaphylactic reactions, normal reaction to allergens, inflammation in nasal membranes and can lead to mucosal edema, bronchial constriction and epithelial damage
What type of reaction is cytotoxic and antibody mediated?
type 2
What are examples of a Type 2 reaction?
blood transfusion, drug reactions
Which type of reaction involves antigen-antibody (immune) complexes?
Type 3
what are the manifestations of a type 3 reaction?
inflammation, chills, fever, rash, arthritis
which type of reaction is cell-mediated and is delayed?
Type 4
What are examples of a Type 3 reaction?
glomerulonephritis, SLE and rheumatoid arthritis
What are the two types of Types 4 reactions?
direct (CD8 cells) and delayed type (CD4 cells)
what are manifestations of a type 4 reaction?
rash, fever, multiorgan involvement
what are examples of Type 4 reaction?
allergic contact dermatitis, hypersensitivity dermatitis, hypersensitivity pneumonitis, transplantation rejection
what are common unifying features of hypersensitivity disorders?
anaphylaxis, inflammation, fever
which cells are involved in a Type 1 reaction?
Helper T cells, mast cells or basophils, lipid mediators, cytokines, eosinophils
what is the role of the Helper T cells in a type 1 reaction?
T1H cells stimulate the differentiation of B cells; T2H cells direct B lymphocytes to switch class and produce IgE antibodies
what is the role of mast cells/basophils in a type 1 reaction?
they degranulate, releasing histamine, and cause vasodilation which leads to anaphylaxis
what is a primary reaction in Type 1?
within 5-30 minutes of exposure; subsides within 60 minutes; mediated by acute mast cell degranulation
what is a secondary reaction in Type 1?
within 2-8 hours; can last for several days; results from the release of cytokines and lipid mediators; role of eosinophils
what is anaphylaxis?
a systemic response to the inflammatory mediators released in Type 1 reaction
