Lecture 19

Question 1

What happens during the early phase of the innate immune system?

Answer 1

• defensins and other preformed effectors such as lysozyme
• C3b binds to pathogen
• resident MPs and mast cells detect bacteria with TLRs and release cytokines
• C3b and scavenger receptors help macrophage
• phagosome maturation
• cytokines released by the resident macrophages and resident mast cells start the induced phase

Question 2

what happens in the acute phase response? (in between early and induced)

Answer 2

IL-6 starts production of C-reactive protein and MBL
- they act like antibodies and activate complement and function as opsonins

Question 3

How do neutrophils get recruited into the infection site?

Answer 3

• adhesion molecules
• histamine causes vasodilation
• TNF-alpha, leukotrine B4, C5a– transport P selectin in Weibel-Palade bodies to the cell surface
• TNF-a starts transcription of E-selectin and ICAM-1 genes
• IL-1B stimulates G-CSF production– more neutrophils

Question 4

What is tethering?

Answer 4

• capturing free flowing neutrophils and monocytes from the blood to the endothelium
• P and E selectins of the endothelium bind specific carbohydrate (Sialyl-Lewis X)
• ICAM-integrin interaction strengthens and the cell pushes inbetween the endothelial cells

Question 5

How do neutrophils get from the blood vessel wall to the tissue?

Answer 5

the neutrophil digests the basement membrane and a monocyte repairs it

Question 6

Does the leukocyte disrupt the blood vessel wall when it pushes through?

Answer 6

no– squeezes between cells that express CD31, and forms and breaks these interactions to squeeze through like gears

Question 7

What are the two types of receptors on neutrophils and macrophages?

Answer 7

opsonic and non-opsonic

Question 8

How do activated neutrophils kill extracellular pathogens?

Answer 8

with NETs (made out of chromatin and neutrophil granular proteins)

Question 9

What happens during the DC maturation process?

Answer 9

• more expression of MHC class I/II, costimulatory and cell adhesion molecules on the cell surface
• process pathogen
• display the dendrites to facilitate interactions with T cells

Question 10

What is the job of the dendritic cell?

Answer 10

1. determine what kind of pathogen is causing the infection
2. guide the polarization of naive CD4 T cells towards the appropriate effector CD4 T cell

Question 11

How does the phagolysosome break down pathogen?

Answer 11

NADPH +2O2 —> NADP+ +@O2- +2H+
- This produces NADPH oxidase and reactive nitrogen species

Question 12

What triggers the activation of NADPH oxidase?

Answer 12

phosphorylation of all NADPH oxidase and moving all the subunits to the plasma membrane