IMMUNITY

IMMUNITY I

Orginization & function of the immune system Innate & Adaptive Immunity: The cellular & the mediator events of the acute inflammatory response play a key role in the first line or innate immunity against infection, if this failed to provide an adaptive immune system occurs, which mediated by lymphocyte which express antigen specific receptors.

Clinical immunology

Important cells are: 1- Ag presenting cells 2- Neutrophils polymorphs 3- Macrophages 4- Natural killer cells 5- Eosinophils 6- T-Lymphocytes 7- B-Lymphocytes 8- Mast cells

Charasteristic features of adaptive immunity: 1.Specifity: Distinct antigens generate specific response 2. Diversity: Antigens are recognized by different lymphocytes 3. Memory: Re-exposure to antigen induce more rapid & effective response 4.Self regulation: Normal immune response decrease with time 5.Self non self discrimination: During development lymphocytes learn to distinguish between self & foreign antigen

T - cell Mediated immunity:

Helper ( CD 4+) T Cells: These cells differentiate into either Inflammatory (TH 1) or Helper (TH2) cells. Both subsets produce: 1. Interleukin(IL-3) 2. Tissue necrosis factor (TNF - alpha) 3. Granulocyte - macrophage colony stimulating factor (GM-CSF) TH 1 also: 1. IL - 2 & Interferon (IFN) production 2. Promote induction of cytotoxic cells 3. The activation of macrophage & NK cell 4. B - cell differentiation & synthesis 5. Mediate delayed-type hypersensitivity response 6. Promote the killing of intracellular bacteria


Cytokines & Chemokines: Cytokines are often made by several different cell types, they have shared characteristics in that key are antigen non-specific, synthesized & rapidly secreted & in general, have short half lives, their primary function is to regulate immune responses. Cytokines receptors can be categorized into 4 families namely: 1. Ig super family (eg. IL_1) 2. Haemopoetic receptor family (ex.erythropoietin & GM-CSF) 3.TNF family (receptor I & II ) 4.Chemokine receptor family