Hypersensivity

Hypersensivity
Lecture (11) •
Dr.Baha, Hamdi . AL-Amiedi •
Ph.D. Microbiology •

In immunity focus of attention is antigen (Killing , neutralization of toxin).
in hypersensitivity focus of attention is
what happens to host as a result of immune reaction.
Some forms of’ immune reaction can produce sever and occasionally Fatal results. This are known hypersensitivity.
Mechanismes
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 used:
Hypersensivity type-1
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