Download - Interleukins (IL) : cytokines that are secrected by leukocytes and act upon other leukocytes
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.
Most cytokines exhibit autocrine and/or paracrine action
Properties of Cytokines:
• Pleiotrophy
• Redundancy
• Synergy
• Antagonism
• Cascade induction
REDUNDANCY
ELISA assay of cytokines
Cytokines Belong to 4 Structural Families:
• Hematopoietin family
• Interferon family
• Chemokine family
• Tumor necrosis factor family
The two majorcytokine 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
Subfamilies in Class I Cytokine Receptors
CNTF: ciliary Neurotrophic factor
LIF/OSM: leukemia-Inhibitory factor/oncostatin
Antagonistic Effects between Cykotines
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 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 cells promote 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 cells stimulate 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
Cross-regulation between IFN- and IL-4
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-.
• Bacterial toxic shock: caused by superantigens that bind simultaneously to MHC class II and TCR V 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
Cytokines in hematopoiesis