Hypersensitivity

HYPERSENSIVITY•
Dr.Baha, Hamdi . AL-Amiedi •
The mechanisum of hypersensitivity is that • reactions that appear within minutes are mediated by freely diffusible antibody molecules ( immediate type).
The other type is slow evolving responses that • are mediated by sensitized T- lymphoeytes.
This cell mediated Hypersensitivity(delayed
type)
Coombs and Gell Classification (1969 ) They • are classified hypersensitivity reaction into (4) types on the basis of pathogenesis .It is widely use
Antigens which consist of foreign peptide involves the activation of mast cell (in tissue)& basinophiles (in circulation) leading to the production of IgE, upon binding of allergen to cell-associated IgE release of histamine from mast cell, basinophiles which is responsible for allergy symptoms. Once the body reexposed these occur in
Atopic disease like Asthma, acezema Type II hypersensitivity –(cytotoxic) immune-
mediated destruction of red blood celDrug (penicillin) modified red blood cells induce the production of antibodies, because the bound drug (as Haptin) makes them look foreign to the immune system.
When these antibodies are bound to them, the red blood cells are more susceptible to lysis or phagocytosis. Onset is dependent on the presence of specific antibodies Type II hypersensitivity –(cytotoxic) immune-
mediated destruction of red blood cells
Drug (penicillin) modified red blood cells induce the production of antibodies, because the bound drug (as Haptin) makes them look foreign to the immune systeml