introduction to immunology part 2

Question 1

What is phagocytosis

Answer 1

A specific form of endocytosis by which cells internalise solid matter, including apoptotic cells and microbial pathogens.

Question 2

Which cells excel in phagocytosis

Answer 2

Macrophages, neutrophils and immature dendritic cells.

Question 3

What are the steps of phagocytosis

Answer 3

1. macrophages express a set of PRRs.
2. receptor binding to PAMPs signals the formation of a phagocytic cup.
3. Cup extends around the target and pinches off, forming a phagosome.
4. fusion with lysosomes to form a phagolysosome- killing of pathogens and degradation of contents.
5. Debris is released into extracellular fluid.
6. Pathogen-derived peptides are expressed on special cell surface receptors
7. Pro-inflammatory mediators are released.

Question 4

What is opsonisation

Answer 4

Opsonisation is the coating of pathogens by soluble factors (opsonins) to enhance phagocytosis.

Question 5

What are some examples of opsonins

Answer 5

C3b
C-reactive protein (CRP)
IgG/IgM

Question 6

summarise early innate immune response

Answer 6

pathogens killed-> infected cells killed->production of pro-inflammatory mediators.
nitric oxide, prostaglandin/leukotrienes, histamines, pro-inflammatory cytokines.
->localised, acute inflammation.

Question 7

What does inflammation promote

Answer 7

Vascular changes
recruitment and activation of neutrophils
bacteria produce chemicals that attract neutrophils to the site of infection

Question 8

What is diapedesis

Answer 8

migration of neutrophils across the endothelium.

Question 9

What do neutrophils do.

Answer 9

In infected tissues, pathogens release chemical signals that attract neutrophils, neutrophils use pattern recognition receptors to bind to and phagocytose these pathogens. kill internalised pathogens via two distinct mechanisms.

Question 10

What is the Acute Phase Response

Answer 10

involves changes in the plasma concentrations of specific proteins in response to inflammation:
driven by pro-inflammatory mediators released by activated macrophages
mediated by liver hepatocytes which produce a variety of acute phase proteins
-> C3 and MBL
-> C reactive protein (CRP)- primes certain bacteria for destruction by the complement system, has a prognostic role(severity, duration f inflammation)

Question 11

what do virally-infected cells produce and release

Answer 11

Cytokines called interferons.