Innate Immunity

Question 1

name 3 external defenses

Answer 1

physical barriers- skin
secretions from epithelia- sweat, saliva, gastric fluid
microbial competition- non pathological bacteria can be toxic to bad bacteria

Question 2

complement

Answer 2

20 distinct/interdependent proteins that may contribute to an inflammatory response either directly (alternative pathway) or via antibodies (classical pathway)

The process

1. initiate inflammation
2. attract neutrophils
3. enhance attachment of microbes to phagocytes
4. kill the microbe

Question 3

acute phase proteins

Answer 3

a heterogenous group of proteins mostly produced by the liver important in innate immunity

Question 4

c-reactive protein CRP

Answer 4

binds bacterial phophoryl cholin, activates C

Question 5

serym amyloid A SAA

Answer 5

activates C, acts opsonin

Question 6

mannose binding protein MBP

Answer 6

binds mannose on bacteria (opsonization), activates C

Question 7

metal binding proteins

Answer 7

removes metal ions required for bacterial growth

Question 8

anti-trypsin, anti-chymotrypsin

Answer 8

protease inhibitors

Question 9

interferons

Answer 9

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

Question 10

collectins

Answer 10

carbohydrate binding proteins that act as opsonins

Question 11

defensins

Answer 11

act as peptide antibiotics

Question 12

pattern recognition receptors

Answer 12

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

Question 13

mannose receptors

Answer 13

expressed on macrophages. DCs, and endothelial cells. bind to mannose carbohydrates on microbes, phagocytose the microbe, and present the antigens on MHC molecules

Question 14

CD14

Answer 14

binds LPS on gram negative bacteria. found on macrophages

Question 15

scavenger receptors

Answer 15

recognize carbohydrates or lipids. found on macrophages

Question 16

toll like receptors

Answer 16

recognize molecular patterns from a range of pathogens (LPS, pepitdoglycans, glucans) found on APCs, macrophages and other lymphocytes

Question 17

describe the different types of macrophages and where they are found

Answer 17

monocytes- blood stream
kupffer cells- liver
mesangial cells- kidney
alveolar macrophages- lungs
microglial cells- brain

Question 18

describe the stages of macrophage phagocytosis

Answer 18

1. movement to microbe using chemotactic signals (C, MDP)
2. attachment to microbe using mannose, C, or Fc receptors
3. endocytosis into phagosome
4. fusion of phagosome with lysosome
5. killing of microbe using ROS or NO

Question 19

what are the two unique pathways that macrophages can be stimulated into?

Answer 19

1. proinflammatory

2. wound healing, suppression of lymphocytes, pro-rebuilding

Question 20

in tissues, what state are dendritic cells found in?

Answer 20

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

Question 21

what are the different types of DCs?

Answer 21

Langerhans cells- found in the skin
interdigicating cells- found in the t cell area of lymph nodes
follicular dendritic cells- b cell follicles

Question 22

what type of infection are neutrophils best at responding to?

Answer 22

bacterial

Question 23

describe how neutrophils exit circulation

Answer 23

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

Question 24

how do NK cells kill?

Answer 24

perforin-containing granules
Fas-Fas ligand
TNF-a release

Question 25

what is the “fail safe” mechanism for NK cells

Answer 25

they have receptors to bind MHC class 1 receptors to prevent auto activation

Question 26

what is the difference between where mast and basophils are found?

Answer 26

mast cells- CT and mucosal surfaces

basophils- in circulation

Question 27

what are some mediators released by mast cells and basophils and what do they do?

Answer 27

histamine- vasodilation/vascular permeability
TNFa/IL8/IL5- attract neutrophils and eosinophils
platelet activating factor- attract basophils

Question 28

what do eosinophils work against?

Answer 28

parasites- they kill them by releasing major basic protein

Question 29

how do platelets contribute to immunity?

Answer 29

hep initiate complement activation

Question 30

list some effects of IL12

Answer 30

produced by macrophage in response to autocrine TNF-a

recruits PMN
activates NK cells to make IFN-y- activates macrophages
NK cells upregulate IL2 receptors

Question 31

what are important activators of t-cell immunity

Answer 31

TNF-a, IL12, IFN-y

Question 32

what do virally infected cells release that causes antiviral responses in nearby cells?

Answer 32

IFN-a and b. This also activates NK cells to come fuck up the viruses