innate immunity Flashcards
immune cells involved in innate immunity
neutrophils, macrophages, dendritic cells, eosinophils, mast cells, natural killer cells
2 key players in pathogen recognition
- PAMPs
2. TLR
PAMPS
pathogen associated microbial pattern- lipopolysaccarides on the outside of gram (-) bacteria, cell wall polysaccharide from fungi, double strand RNA from viruses- PAMPs bind to leukocyte pattern recognition receptors (PRR) and activate leukocytes to kill or ingest pathogens
TLR
toll-like receptor - single pass transmembrane protien on the membrane of leukocyte and non-immune cells, 10 TLR identified in humans, varying in immune cell distribution and PAMP recognition
they link innate and adaptive immunity on dendritic cells
imiquimod
topical cream for warts, acitic keratoses and basal cell carcinoma - activates TLR7 enhancing innate immunity through secretion of cytokines (IFD, IF6, TNFD) - activate langerhan, NK, macrophage, B cells, treats HPV and anti-tumor- innate and adaptave
function of chemotaxin and examples
chemotaxins are chemicals that attract leukocytes to the site of infection - macrophage chemoattractant protein-1 (MCP-1), IL8
role of adhesion molecule in leukocyte extravasation
extravasation: leave blood vessel for tissue
ICAM-1: intracellular adhesion molecule on the epi attach to LFA-1 to trigger inflammation
LAD1
(leukocyte adhesion deficiency) LAD1 is caused by molecular deficits in LFA (lymphocyte function-associated antigen 1), leading to ineffective migration and phagocytosis
Recurring bacterial infection, ineffective wound healing, impaired pus formation, and granulocytosis (increased level of granulocytes in peripheral blood)
Describe the role of opsonins in phagocytosis
Opsonins: antibodies and plasma proteins that tag particles to be ingested
Here the antibodies bridge the gap between the pathogen and the macrophage to facilitate its elimination
Describe the major functions of NK cells in innate immunity
NK cells target virus-infected cells and induce apoptosis, act faster than lymphocytes
NK cells attach some tumor cells
Recognize virus-infected cells via DAMPs
NK cells and other lymphocytes secrete antiviral cytokines, including interferons (IFNs)
three functions of interferons
Interfere with viral replication
IFN-y activates macrophages and other immune cells
Can cause fever, muscle pain, and flu-like symptoms
Describe the property and functions of acute‐phase proteins
Plasma levels increase immediately after injury or infection, and declines as the immune response proceeds
Mostly produced in the liver
Includes opsonins, antiprotease molecules (prevent tissue damage), and c-reactive protein (CRP)
CRP
Binds to lysophosphocholine on the surface of dead or dying cells and some bacteria, and activates the complement system, promoting phagocytosis by macrophages
Is an indicator of chronic inflammation (its level correlates with risk for CHD)
two immune cells that synthesize and release histamine
Basophils and mast cells
Basophils and mast cells role in inflammation initiation
Dilates blood vessels
Increases capillary permeability, plasma proteins escape into the interstitial space, leading to local edema
Works with prostaglandins and leukotrienes to induce bronchoconstriction
Describe the two points of regulation of eicosanoids synthesis during inflammation
Cyclooxygenase pathway:
Lipoxygenase pathway:
Cytokines and complement stimulate the enzymatic release of arachidonic acid from plasma membrane (glucocorticoids)
Lipoxygenase pathway:
Leukotrienes cause bronchoconstriction
Lypoxins modulate the actions of leukotrienes and cytokines (resolution of inflammation)
Cyclooxygenase pathway
COX-2 is induced by LPS, TNF-a, and IL-1, and inhibited by glucocorticoids
PGE2s cause vasodilation, hyperalgesia, and fever
Two major cytokines involved in acute inflammatory response
IL-1, TNF-a
IL-1
Stimulate hepatic production of acute-phase proteins
Alter vascular endothelium to facilitate passage of leukocytes and proteins
Induce fever
Stimulate cytokine secretion
TNF-a
Produce chiefly by activated macrophages Stimulate hepatic production of acute-phase proteins Neutrophil chemoattractant Pyrogenic Induce apoptosis
Describe the three functions of bradykinin
Vasodilation, lower BP
Increase vascular permeability
Promotes pain sensation
four functions of complement proteins
- Actasopsonins C3b
- Actasleukocyteattractants on c3a
- Inducemastcelldegranulation C39/5a
- Formmembraneattackcomplex (MAC)tolysethetargetcells
MAC
- complement insert into membrane of pathogen, creating pores, pores of membrane attack complex, water and ions enter through the pores of the embrane attack complexes, cell swells and lyses
acute phase proteins
liver proteins that act as opsonins and enhance inflammatory response
pyrogens
fever producing
cytokines
proteins released by one cell that affects growth or activity of another cell
opsonins
proteins that coat pathogens so phagocytes recognize and ingest
antibodies
proteins secreted by B lymph that fight invaders
bradykinin
stimulates pain receptors, vasodilator
complement
plasma and cell membrane proteins that act as opsonins, cytolytic agents, and mediators of inflammation
C-reactive protein (CRP)
opsonin that activates complement cascade
granzymes
cytotoxic enzymes that initiate apoptosis
histamine
vasodilator and bronchoconstrictor, released by mast cells and basophils
interferons
inhibit viral replication and modulate the immune response
interleukins
cytokines secreted by leukocytes to act primarily on other leukocytes; IL-1 mediates inflammatory response and induces fever
kinins
plasma proteins that activate to form bradykinin
lysozyme
extracellular enzyme that attacks bacteria
MHC
membrane protein complex involved in cell recognition
MAC
pore protein made in complement cascade
perforin
pore protein that allows granzymes to enter cell make by NK and cytotoxic T cell
suberoxide anion
powerful in phagocyte lysosomes
T-cell receptors
T lymphocytes that recognize and bind antigen presented by MHC
TNF
tumor necrosis factor- t lymph receptors that recognize and bind antigen presented by MHC receptors
