Post on 22-May-2015
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
THANK you