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41 Cards in this Set

  • Front
  • Back
Define innate immunity
form of immunity that exist before exposure to pathogens; hard wired, rapid, and recognizes conserved patterns on pathogens
4 major characteristics of innate immunity
1. Limited repertoire of receptors
2. Ancient system
3. Intimately intertwined with the adaptive immune system
4.Invariant and constant
What is the major cellular response of innate immunity
Inflammation or the Inflammatory response
The 4 players that participate in the generation of inflammation
Tissues, Early soluble mediators, cells, other soluble mediators
What are the barriers to pathogen entry
Physical (External skin and internal mucosa)
Chemical (Fatty acids, Mucus and saliva, Cationic antimicrobial peptides)
What are the early soluble inflammatory mediators
Bradykinin, Histamine, Complement, Lipid mediators, Platelet activating factor
What does bradykinin do
Stimulates neutrophil migration, macrophage release of cytokines; induces histamine release; activates complement; vasodilation, pain, edema
What does histamine do
Bronchoconstriction, vasodilation, pruritis
What does complement do
Vasodilation, edema, opsonization
What do lipid mediators do
Cell activation
What does platelet activating factor do
Neutrophil recruitment and activation
What are the three major C' mediated pathways
1. Alternative pathway (pathogen surface)
2. Lectin pathway (mannose-binding lectins bind to pathogen surface)
3. Classical (Antibody binds to pathogen antigen)
Where are two places C' receptors are found
Neutrophils and macrophages. These facilitate uptake by phagocytosis
What are the two major biologic functions of C'
Opsonization and Chemotaxis
Which host cells are involved in innate immunity
Neutrophils, Tissue macrophages, mast cells, immature dendritic cells, NK cells, lymphocytes
What is the role of neutrophils in innate immunity
Most abundant phagocytes, first cells recruited, relatively short lived
What is the role of tissue macrophages in innate immunity
Mature form of monocytes, can undergo division at inflammatory sites, dominant effector cells of the second stage of the innate immmune response, set the stage for adaptive immunity
Discuss Mast cells in innate immunity
Located on surfaces (skin, GI tract, respiratory tract, connective tissues); preformed granules of cytokines and histamine; after activation secrete TNF-a, IL-4, IL-5, IL-6, IL-8
Which cells are usually first to interact with antigen in the skin and mucosa
Immature dendritic cells
What do NK cells express
Inhibitory receptors that recognize MHC class 1. They are thus activated by target cells lacking MHC class 1
What do macrophages and mast cells do upon phagocytosis of pathogens in the tissues?
Synthesize and secrete a panel of soluble mediators that play a role in the local stimulation of the localized inflammatory response and also have systemic effects
What are the major cytokines
IL-1B, TNF-a, IL-6, IL-8, IL-12, Type 1 interferons
What does IL-1b do
Activates vascular endothelium, induces the acute phase
What does Il-8 do
Chemotactic cytokine
What does TNF-a do
Activates vascular endothelium, induces the acute phase response
What does IL-6 do
Activates lymphocytes and induces the acute phase response
What does IL-12 do
Activates NK cells leading to cytokine production, especially IFN-g
What do Type 1 and a/B interferons do
Activate NK cells to kill virus-infected cells
What three cytokines induce the acute phase response
IL-1B, TNF-a, IL-6
What are acute phase proteins (ACP)
Soluble plasma proteins secreted by hepatocytes in the liver in response to acute infection
What two acute phase proteins enhance the fixation of C' at the pathogen surface
C-Reactive protein (binds PC on bacteria)
Mannose-binding protein (MBP)(initiates lectin-binding C' pathway)
The process of leukocyte migration to sites of infection is initiated by
Activated tissue macrophages and mast cells at the site of infection
Activated macrophages and mast cells at the site of infection causes
Increased vascular permeability, increases in adhesion molecule expression, secrection of cytokines and chemokines
What is the multi-step model of leukocyte migration
Rolling of leukocytes on the endothelium, activation of leukocytes, stable adherence to the endothelium, transmigration
The process of leukocyte migration to sites of infection is stimulated by
Cytokines, especially TNF-a
What are Pathogen Associated Molecular Patterns (PAMPS)
Conserved molecules produced only by microbes and not by the host organism
What are Pattern Recognition Receptors (PRR)
A set of germline encoded receptors that recognize PAMPS and thus are specific for non-self structures
Name two common PRRs
Toll-like Receptors and Seven transmembrane a-helical receptors
Name 4 phagocytic receptors
Mannose receptors, Scavenger receptors, Fc receptors, Mac-1 (integrin)
What are two chemicals used to kill microbes
Reactive oxygen intermediates (ROIs) and Nitric oxide (NO)
How is NO created in macrophages
The inducible Nitric oxide (iNOS) system