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Cytokines : low-molecular-weight proteins secreted by WBC or other cell types in response to a number of stimuli. Interleukins (IL) : cytokines that are secrected by leukocytes and act upon other leukocytes.
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Cytokines: low-molecular-weight proteins secreted by WBC or other cell types in response to a number of stimuli. Interleukins (IL): cytokines that are secrected by leukocytes and act upon other leukocytes. Chemokines: cytokines that stimulate the migration and activation of cells, especially phagocytes and lymphocytes. They have a central role in inflammatory responses.
Properties of Cytokines: • Pleiotrophy • Redundancy • Synergy • Antagonism • Cascade induction
Cytokines Belong to 4 Structural Families: • Hematopoietin family • Interferon family • Chemokine family • Tumor necrosis factor family
The two major cytokine producers; TH cell and macrophage
Cytokine Receptors Belongs to 5 Families: • Immunoglobulin superfamily receptors • Hematopoietin receptor family • Interferon receptor family • TNF receptor family • Chemokine receptor family
CNTF: ciliary Neurotrophic factor LIF/OSM: leukemia- Inhibitory factor/ oncostatin
Cytokine Antagonists IL-1 receptor antagonist (IL-1Ra):binds to the IL-1 receptor but has no activity. Soluble IL-2 receptor (sIL-2R):a segment of the a subunit that can bind to IL-2 and prevent its interaction with membrane-bound IL-2 receptor. Viral mimics of cytokines and cytokine receptors
Suppress TH1 response
TH1 and TH2 cells can be identified in vitro by the cytokines they secrete: • TH1 cellspromote cell-mediated immunity (e.g., activation of TC cells and delayed-type hypersensitivity) and the production of opsonization IgG antibodies. They are also associated with inflammation. • TH2 cellsstimulate eosinophil activation and differentiation and promote humoral response (secretion of IgM and IgE antibodies). They are related to allergic reactions.
Cytokine-mediated generation and cross regulation of TH subsets
The TH1/TH2 Balance Determines Disease Outcomes Leprosy: a disease caused by an intracellular pathogen Mycobacterium leprae. Tuberculoid leprosy: a cell-mediated immune response forms granulomas, resulting in the destruction of most of the mycobacteria. Lepromatous leprosy: humoral response dominates, sometimes resulting in hypergammaglobulinemia. High numbers of the bacteria in macrophages. The infection will progress and spread into the bone and cartilage with extensive nerve damage.
Cytokine-related Diseases • Bacterial septic shock: endotoxin in cell wall of gram-negative bacteria stimulate macrophages to over produce IL-1 and TNF-a. • Bacterial toxic shock: caused by superantigens that bind simultaneously to MHC class II and TCR Vb domain. 5-25% of total T cells may respond to a single superantigen and result in excessive production of cytokines.
Strategies help to prolong the survival of heart transplants