Role of cytokines in type IV hypersensitivity

Eman abd el-raouf ahmad youssif

The content:

Introduction-

*type IV reaction

*cytokines

-role of cytokines(mechanism)

introduction

introduction

General mechanism

General mechanism

definition(type 4 hypersensitivity)

Type 4 hypersensitivity is often called delayed type hypersensitivity as the reaction takes two to three days to develop.

CD4+ helper T cells recognize antigen in a complex with Class 2 major histocompatibility complex. The antigen-presenting cells in this case are macrophages that secrete IL-12, which stimulates the proliferation of further CD4+ Th1 cells. CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Th1 cytokines, thus mediating the immune response. Activated CD8+ T cells destroy target cells on contact, whereas activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells

Hero's of type 4 hypersensitivity

TDTH cells/TC/Th1

Cytokines:IL-2,MIF,TNF,interferon.

Macrophages ,lytic enz.

Type 4 hypersensitivityContact hypersensitivity

Small molecules

complex with skin proteins

Complex internalized by

APCResponse 48-72 hrs

T4 granulomas

Effective against intracellular parasites

Granulomatous lesions

Tuberculosis

Figure 44–4 • Type IV hypersensitivity. Type IV responses are mediated by T cells through three different pathways. In the first, type 1 helper T (TH1) cells recognize soluble antigens and release interferon-γ (IFN-γ) to activate effector cells, in this case macrophages (Mø), and cause tissue injury. In TH2-mediated responses, eosinophil's predominate. TH2 cells produce cytokines to recruit and activate eosinophil, leading to their degranulation and tissue injury lymphocytes (CTLs). In the third pathway, damage is caused

directly by cytolytic T. IL, interleukin".

Example of type 4 hypersensitivity

Contact dermatitis (poison ivy rash, for example)Temporal arteritisSymptoms of leprosySymptoms of tuberculosisTransplant rejectionCoeliac disease

Mechanism-contact dermatitis

Contact dermatitis

References:://http

. . . . / /18409354www ncbi nlm nih gov pubmed

://http. . . / / /www cartage org lb en themes sciences

/ / /lifescience generalbiology Immunology/ /ImmuneSystemDisease Hypersensitivit

/ / .y TypeIV TypeIV htm

://http. . . / . ? =10www frca co uk article aspx articleid

0083://http

. . . / / /www hse gov uk skin professional cause/ .s dermatitis htm

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