Type 4 hypersensitivity | Immunology | First Aid Lectures | Lec25 #drjamillectures #drjameellectures
Channel: Dr. Jamil Lectures
Date: 2022-04-11

In this lecture we will discuss about type 4 hypersensitivity involving two mechanisms;1)CH4+ T helper cell 1 involvment  2) CD8+ cytotoxic cell invilvement
Tuberculin type hypersensitivity,Lepromin test,Contact hypersensitivity,contact dermatitis

https://youtu.be/9H1IEYH14f0
https://youtu.be/2UJeTuPfNww
https://youtu.be/aP06bUvyqCA

Instagram account  dr_jamil56

Type 4 hypersensitivity
Two mechanisms, each involving T cells:
1. Direct cell cytotoxicity: CD8+ cytotoxic T cells kill targeted cells.
2. Inflammatory reaction: effector CD4+ T cells recognize antigen and release inflammation-inducing cytokines (shown in illustration)
Response does not involve antibodies (vs types I, II, and III).
Examples: contact dermatitis (eg, poison ivy, nickel allergy) and graft-versus-host disease.
Tests: PPD for TB infection; patch test for contact dermatitis; Candida skin test for T cell immune function.
4T’s: T cells, Transplant rejections, TB skin 
tests, Touching (contact dermatitis).




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