Lecture 22 - Innate Immunology

Question 1

How do phagocytes recognize and engulf external pathogens?

Answer 1

It uses the toll-like receptor present on the membranes.

Question 2

How do phagocytes recognize internal pathogens?

Answer 2

It uses NOD-like receptor and/or RIG1-like receptor in the cytoplasm.

Question 3

What happens during phagocytosis?

Answer 3

1. Phagocyte engulfs bacteria, vesicle is the phagosome
2. Phagosome fuses with lysosome, making it a phagolysosome
3. Release digestive enzyme and a oxidative burst

Question 4

What are four ways in which the pathogens can resist being destroyed?

Answer 4

1. antioxidants to fight oxidative burst
2. oxidants to kill phagocyte
3. toxins called leukocidins to kill PMNs and monocytes
4. prevent phagocytosis with capsules

Question 5

What is granoluma?

Answer 5

a sac like structure formed by the fusion of phagocytes (macrophages, giant cells, and T cells)

Question 6

What disease is well known for granuloma formation?

Answer 6

in tuberculosis, bacteria break out the granulomas

Question 7

What are the antigen presenting cells?

Answer 7

B cells (lymphocyte)
Macrophages (phagocyte)
Dendritic cell (phagocyte)

Question 8

What is MHCI?

Answer 8

Major histocompatibility complex I - Mounts antigen from cytoplasm. Found on all nucleated cells

Question 9

What is MHC2?

Answer 9

Major histocompatibility complex II - Mounts antigens from phagolysosome. Found only on APCs

Question 10

Why do MHC protein have to matched for tissue allografts?

Answer 10

allografts are form other sources, so if their MHC proteins are different, the body will try to eliminate it

Question 11

MHC1 presents both ____ and_________ equally

Answer 11

self and non-self

Question 12

What is the difference between recruiting Tc cells and Th cells?

Answer 12

Tc cells are recruited by MHCI to kill the infected cell

Th cells are recruited by MHCII to activate the adaptive immune response

Question 13

What are interferons?

Answer 13

induced by viral infected cells when RLR binds to viral nucleic acid.
interferon diffuses to neighboring cells and induces synthesis of antiviral proteins

Question 14

What are three outcomes of the complement system?

Answer 14

1. Release cytokines to induce inflammation
2. Build the membrane attack complex and insert it in a foreign cell
3. opsonize foreign cell

Question 15

What are the different way to activate the complement system?

Answer 15

1. Classical pathway
2. Alternate (properdin) pathway
3. Mannan-binding lectin pathway

Question 16

How does the classical pathway work?

Answer 16

1. Antibodies/immunoglobulins bind to bacterial surface antigens
2. Uses many complement proteins, start with C1
3. C3a induces vascular permeability
4. C2a, C3b, C4b make convertase
5. C5a attracts phagocytes
6. C5b recruits rest of membrane attack complex

Question 17

How does the alternate (properdin) pathway work?

Answer 17

1. Uses many complement proteins, start with C3
2. When C3b binds bacteria it brings in Factor B
3. C3b dimer, Bb, and properdin make convertase
4. C3a, C5a induce inflammation and recruit macrophages
5. C5b recruits rest of MAC

Question 18

How does the Mannan-binding lectin (MBL) pathway work?

Answer 18

1. MBL binds mannose and N-acetyl-glucosamine on bacterial cell
2. C2a, C3b, C4b make convertase
3. C3a, C5a induce inflammation and recruit macrophages
4. C5b recruits rest of MAC