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TYPE 1V HYPERSENSITIVITY

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TYPE 1V HYPERSENSITIVITY

Post  sudheerkher on Fri Nov 14, 2008 1:25 am

TYPE 1V HYPERSENSITIVITY
DELAYED OR CELL MEDIATED HYPERSENSITIVITY

This is a cell mediated response. These are provoked by intracellular microbial or hapten like simple chemicals on the skin. They evolve slowly and consist of mixed cellular reaction involving lymphocytes and macrophages. Here the reaction is produced by sensitized T cells, which on contact with the specific antigen release cytokines that cause a biological effect on leukocytes, macrophages and tissue cells.

Delayed hypersensitivity can be transferred by lymphocytes or the transfer factor and not by serum. There are two types of delayed hypersensitivity:-

TUBERCULIN (INFECTION) TYPE: TUBERCULIN REACTION. Small dose of tuberculin is injected intradermally in an individual already sensitized to tuberculoprotein by prior infection or immunization, an indurated inflammatory reaction develops at the site within 48-72 hrs. there is no response in individuals without prior sensization. Tuberculin type is seen in bacterial, viral, fungi and parasitic infections especially when it is subacute or chronic and an intracellular pathogen.

CONTACT DERMATITIS TYPE:- This is as a result of skin contact with a variety of chemicals-metals such as penicillin, nickel etc. sensitization is particularly liable if it is in an inflamed area of skin or when the chemical is in oily base and it requires percutaneous absorption. As most are fat soluble, there entry is through the sebaceous glands. These substances are themselves not antigenic but acquire antigenicity on combination with skin proteins.
By kauthar Tofa
2006M030

sudheerkher

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