Infection and innate immunity

Question 1

What is innate immunity

Answer 1

all living things are able to discriminate between self and non-self

Question 2

Describe innate immunity

Answer 2

provides first line or immediate response to pathogen invasion

more primordial than adaptive immunity

has no memory. It is what you are born with

Question 3

What are the 3 main types of pathogens

Answer 3

Viruses: intracellular pathogens
Bacteria: extracellular P
Protozoa and parasites

Question 4

Describe Viruses: Intracellular pathogens

Answer 4

defense relies on antibodies and cellular immunity- need to be able to distinguish infected from normal cells
eg. Influenza/ polio

Question 5

Describe Bacteria: extracellular pathogens

Answer 5

defense is primarily mediated by innate mechanisms and phagocytosis

Question 6

what are examples of a viruses: Intracellular pathogen

Answer 6

eg. Influenza/ polio, small pox

Question 7

examples of bacteria: extracellular pathogens

Answer 7

Black plague
rheumatic fever
Cholerae

Question 8

Describe Protozoa and parasites

Answer 8

complex multicellular organisms require direct killing by chemical mediators released by specialist myeloid cells

Question 9

What are Granules involvement with Protozoa and Parasites

Answer 9

Granules filled with cytotoxic chemicals. Degranulation releases these toxic inflammatory chemicals such as histamine

Question 10

Describe Neutrophil extravasation steps

Answer 10

1. Activation. Chemokines
2. Tethering
3. Adhesion
4. Diapadesis
5. Chemotaxis

Question 11

Describe Neutrophil extravasation

Activation step

Answer 11

Chemokines from tissue injury or inflammation activate the local endothelial cells lining an adjacent capillary wall

Question 12

Describe Neutrophil extravasation

Tethering step

Answer 12

Neutrophil tethers to the inside capillary wall. mediated by selectins upregulate on endothelial cells and sialyl Lewis X

Question 13

What is sialyl Lewis X

Answer 13

a carbohydrate antigen on neutrophils

Question 14

Describe Neutrophil extravasation

Adhesion step

Answer 14

strong binding between neutrophil integrins and ICAM-1 on the endothelium.
Neutrophil immobilizes and flattens

Question 15

Describe Neutrophil extravasation

Diapadesis step

Answer 15

neutrophils squeeze between endothelial cells into the interstitial space

Question 16

Describe Neutrophil extravasation

Chemotaxis step

Answer 16

Neutrophils migrate along a chemical gradient to the site of the infection

Question 17

what is a FcR

Answer 17

an Antibody

Question 18

Describe the FcR antibody mediated phagocytosis

Answer 18

1. Antibody (IgM and IgG) bind to bacterial antigens
2. Exposes the antibody Fc region
3. Neutrophil FcR binds multivalent Fc
4. Activates phagocytosis
5. Membrane invaginates forming phagosome
6. fuses with lysosome to form phagolysosome
7. Phagolysosome acidifies and superoxide’s kill bacteria

Question 19

What are PAMPS

Answer 19

Pathogen Associated Molecular Patterns

Question 20

Describe PAMPS

Answer 20

Molecules unique to microbes recognised by Pattern recognised receptors

Question 21

Describe PAMPS structures

Answer 21

structurally very complex eg. lipopolysaccharides

evolutionarily stable- dont change much

stimulate the power switch for the adaptive response

Question 22

Describe Toll- Like receptors (TLR)

- Molecular pattern recognition.

Answer 22

Pattern recognition receptors (PRR) bind complex molecules that are unique to microbes

best known are the Toll- like receptors (TLR).

Activation of the TLR stimulates a strong innate response through an important inflammation pathway.

Question 23

Describe the receptor for lipopolysaccharides (LPS)

Answer 23

LPS is a membrane component of all gram negative bacteria

tiny amounts induce a powerful innate response

LPS is a pyrogen- raises temp. It causes fever when injected into the bloodstream

Question 24

What occurs with the release of LPS

Answer 24

released by Gram negative bacterial infections lead to Septic Shock

Question 25

Describe Complement receptors CR1, CR2, CR3, CR4

Answer 25

Myeloid cells receptors that bind activated complement components deposited on bacteria

CR1 is the main neutrophil receptor and binds to C3b
cross linking of the surface CRs initiates phagocytosis