Blood and Immune [Infection & Innate Immunity]

Question 1

3 processes of innate immunity

Answer 1

1. Complement
2. Myeloid cells and phagocytosis
3. Pattern recognition receptors (PRR) which are found on myeloid cells.

Question 2

Bacteria

Answer 2

Extracellular pathogens (mostly).
Defense through innate mechanisms and phagocytosis. 
Distinguished by the gram stain.

Question 3

Protozoa and Parasites

Answer 3

Complex multicellular organisms (worms).
Too big to be engulfed so myeloid cells must secrete inflammatory mediators (degranulation) and granules filled with cytotoxic chemicals that kill.

Question 4

Bacteria: Gram positive

Answer 4

Thick peptidoglycan cell wall. Requires phagocytosis and not killed by complement.

Question 5

Bacteria: gram negative bacteria

Answer 5

Thin peptidoglycan layer surrounded by outer membrane. Can be lysed by complement.

Question 6

Neutrophil Extravasation: Activation

Answer 6

Chemokines from the site activate local endothelial cells lining adjacent capillary wall.

Question 7

Neutrophil Extravasation: Tethering

Answer 7

Neutrophil tethers to the inside capillary wall. Mediated by selecting upregulated on endothelial cells and sialyl Lewis X, a carbohydrate antigen on neutrophils.

Question 8

Neutrophil Extravasation: Adhesion

Answer 8

Strong binding between neutrophil intestine and ICAM-1 on the endothelium. Neutrophil immobilised and flattens.

Question 9

Neutrophil Extravasation: Diapadesis

Answer 9

Neutrophil squeezes between endothelial cells and out of the capillary into the interstitial space (tissue).

Question 10

Neutrophil Extravasation: Chemotaxis

Answer 10

Neutrophil migrates along a chemical gradient to the site of infection.

Question 11

Phagocytosis: ingestion

Answer 11

The bacterium is captured by receptors, membrane invaginates into a phagosome.

Question 12

Phagocytosis: Digestion

Answer 12

Acidification activates protease and stimulates the production of superoxide which kill bacteria.

Question 13

Acronym for phagocytosis steps

Answer 13

I FADE

Question 14

What are TLR’s?

Answer 14

Toll-Like Receptors: PRRs - bind complex molecules unique to microbes. Look like a slinky.
Activation through TLR activates a strong innate response through an inflammatory pathway.

Question 15

What are PAMPs?

Answer 15

Pathogen Associated Molecular Patterns.
Molecules unique to microbes. Recognised by PRRs.
Complex and stable. Stimulate power switch for adaptive response.

Question 16

What is LPS?

Answer 16

Lipopolysaccharide PAMP. A membrane component of all gram negative bacteria. Glycolipid. A pyrogen (causes fever etc.)

Question 17

What’s humoral vs cellular

Answer 17

Humoral is complement and cellular is the other stuff

Question 18

IgG function and serum conc

Answer 18

Complement, foetus
High serum

Most common therefore

Question 19

IgM function

Answer 19

Complement, membrane bound form

Question 20

IgA function

Answer 20

Mucous,

Question 21

IgD

Answer 21

Membrane bound form

Question 22

IgE serum conc and function

Answer 22

High affinity receptor on mast cells

Low serum