Inflammation : Hypersensitivity Flashcards
What is hypersensitivity?
An excessive and potentially harmful immune reaction to a foreign substance not otherwise considered to be noxious
What is type 1 hypersensitivity associated with?
Anaphylactic reactions mediated by IgE
List allergens:
Fungal spores
House dust mites
Pollen
Define allergen
Substance ingested into the body which is recognised as foreign to the body’s immune system resulting in an allergic reaction
How is Chronic type 1 hypersensitivity treated?
Maintaining immunosuppression:
Corticosteroids
Treatment:
Control flares or attacks with corticosteroids
What is type II Hypersensitivity?
Antibody-dependent cytotoxic hypersensitivity
Antibody mediated destruction of cells
Explain type II hypersensitivity.
The antibodies produced by the immune response bind to antigens on the patient’s own cell surface.
Explain type III complex-mediated hypersensitivity
IgM or IgG antibodies form competes with soluble antigen
complexes become deposited in tissues where they activate inflammation, causing tissue damage
Occurs in blood vessels, kidney, joints
Explain Type 4 cell-mediated or delayed hypersensitivity
Pathological reactions to environmental chemicals or persistent microbes (e.g. tuberculosis)
Explain the process of immediate/anaphylactic hypersensitivity
Dendritic cells present allergen to T-cells and B-cells
This triggers an inflammatory response
Allergens trigger a TH2 reaction
IgE antibody is produced
Mast cells present IgE, when allergen comes the mast cells releases (degranulates) its mediators (amines etc.)
What is the mediating cell for hypersensitivity in comparison to inflammation?
Hypersensitivity = Eosinophils (Eos is sensitive to steroids = benefit)
Inflammation = Neutrophil
How is anaphylaxis treated?
Adrenaline injection - vasoconstriction
Beta-adreno receptor agonist
Explain Antibody-dependent cytotoxic hypersensitivity
IgM or IgG to cellular antigen
-e.g. red blood cell from transfusion
Antibodies opsonise cells, activate complete and own cells are phagocytksed.
Explain complex- mediated hypersensitivity
IgM or IgG antibodies form complexes with soluble antigen
These complexes become deposited in tissues where they activate inflammation then causing tissue damage.
This occurs in blood vessels, kidneys and joints
Explain cell mediated or delayed hypersensitivity
Pathological reactions to environmental chemicals or persistent microbes (e.g. tuberculosis)
Activates T-cells and cytokines
