Innate Immunity Flashcards
(32 cards)
name 3 external defenses
physical barriers- skin
secretions from epithelia- sweat, saliva, gastric fluid
microbial competition- non pathological bacteria can be toxic to bad bacteria
complement
20 distinct/interdependent proteins that may contribute to an inflammatory response either directly (alternative pathway) or via antibodies (classical pathway)
The process
- initiate inflammation
- attract neutrophils
- enhance attachment of microbes to phagocytes
- kill the microbe
acute phase proteins
a heterogenous group of proteins mostly produced by the liver important in innate immunity
c-reactive protein CRP
binds bacterial phophoryl cholin, activates C
serym amyloid A SAA
activates C, acts opsonin
mannose binding protein MBP
binds mannose on bacteria (opsonization), activates C
metal binding proteins
removes metal ions required for bacterial growth
anti-trypsin, anti-chymotrypsin
protease inhibitors
interferons
proteins that protect against viral infections
2 types
type 1 (alpha and beta), induced by viruses, some bacteria and cytokines, interfere with viral replication by inhibiting protein synthesis in virally infected cells
type 2(gamma) induced by TCR or NK stimulation, activates macrophages and APC function. found in NK and T cells
collectins
carbohydrate binding proteins that act as opsonins
defensins
act as peptide antibiotics
pattern recognition receptors
recognize ligands found on microbes and not on self. they are encoded via the germ line and are not enhanced with repeated exposures. their activation often leads to upregulation of costimulators
mannose receptors
expressed on macrophages. DCs, and endothelial cells. bind to mannose carbohydrates on microbes, phagocytose the microbe, and present the antigens on MHC molecules
CD14
binds LPS on gram negative bacteria. found on macrophages
scavenger receptors
recognize carbohydrates or lipids. found on macrophages
toll like receptors
recognize molecular patterns from a range of pathogens (LPS, pepitdoglycans, glucans) found on APCs, macrophages and other lymphocytes
describe the different types of macrophages and where they are found
monocytes- blood stream kupffer cells- liver mesangial cells- kidney alveolar macrophages- lungs microglial cells- brain
describe the stages of macrophage phagocytosis
- movement to microbe using chemotactic signals (C, MDP)
- attachment to microbe using mannose, C, or Fc receptors
- endocytosis into phagosome
- fusion of phagosome with lysosome
- killing of microbe using ROS or NO
what are the two unique pathways that macrophages can be stimulated into?
- proinflammatory
2. wound healing, suppression of lymphocytes, pro-rebuilding
in tissues, what state are dendritic cells found in?
they are immature, and phagocytosing surrounding particles. if they are activated, they become mature, stop phagocytosing, upregulate MHC class 1 and 2 receptors, and move to the lymph nodes
what are the different types of DCs?
Langerhans cells- found in the skin
interdigicating cells- found in the t cell area of lymph nodes
follicular dendritic cells- b cell follicles
what type of infection are neutrophils best at responding to?
bacterial
describe how neutrophils exit circulation
when endothelial cells express selectin d/t local inflammation. the neutrophils bind to selectin and it causes them to slow down and roll along the epithelium. If neutrophils pick up inflammatory signals while they are rolling, they upregulate integrins that lock the PMN in place by binding ICAM. PMNs move into cells using a chemokine gradient
how do NK cells kill?
perforin-containing granules
Fas-Fas ligand
TNF-a release
