Overview of the immune system

Question 1

Which cells does HIV affect?

Answer 1

T helper cells- so makes body immunocompromised

Question 2

What can patients develop because of the immunocompromised nature of HIV?

Answer 2

Kaposi’s sarcoma

Question 3

What is a commensal organism?

Answer 3

organism always present in body

do no harm

Question 4

How are commensal organisms protective?

Answer 4

increase competition with pathogenic microorganisms

Question 5

What is the innate immune system responsible for?

Answer 5

non-specific response

Question 6

What makes up the innate immune system?

Answer 6

lysozyme enzyme= present in tears, nasal secretions, sebaceous gland•mucus
cilia lining the trachea
acid in the stomach
commensal organisms in the gut
skin
spermine in sperm
phagocytes

Question 7

Where are phagocytes found?

Answer 7

blood: monocytes
liver: Kupffer cells
kidney: mesangial phagocytes
alveoli: macrophages
connective tissue: histiocytes
brain: microglial cells
spleen: macrophages
lymph nodes: resident and recirculating macrophages
synovial A cells-osteoclasts

Question 8

What are the receptors on phagocytes?

Answer 8

toll like receptor (TLR)

Question 9

What are examples of PAMPS?

Answer 9

lipopolysaccharide in gram negative bacteria
lipoteichoic acid in gram positive bacteria
bacterial DNA sequences (unmethylated CpG)single/double stranded viral RNA
glucans in fungi

Question 10

What do human TLR’s recognise?

Answer 10

PAMPS

Question 11

What is opsonization?

Answer 11

coat microbe with protein (opsonin)
phagocyte has receptor for opsonin
so can detect and kill the pathogen

Question 12

What are examples of opsonins?

Answer 12

antibodies (IgG)

proteins of compliment system (C3b, C4b)

Question 13

What do acute phase proteins and C-reactive proteins do?

Answer 13

cause inflammation

part of innate immunity

Question 14

What is the function of inflammation?

Answer 14

attract cells to site of infection

kill and clear the organisms

Question 15

What do natural killer cells do?

Answer 15

part of innate system
look for changed body antigen
engulf the cells

Question 16

What do interferons do?

Answer 16

interfere with virus- infect other cells

Question 17

What are antibodies made from?

Answer 17

B cells

Question 18

What is the name for 4 chains?

Answer 18

tetrameric

Question 19

What are the 2 types of light chain?

Answer 19

kappa and lambda

but one B cell can only make 1 type of light chain so any antibody can only have kappa or lambda not both

Question 20

What is light chain restriction?

Answer 20

one B cell can only make 1 type of light chain so any antibody can only have kappa or lambda not both

Question 21

Which antibody is made first?

Answer 21

IgM and then IgG

Question 22

What cells recognise the antigens?

Answer 22

T cells recognize antigen processed and presented by antigen presenting cells (dendritic cells are one of the main types)

Question 23

What do antigen presenting cells do?

Answer 23

process peptides from the engulfed pathogens

combine it with their major histocompatibility complex (MHC)

Question 24

What are CD4 T helper cells presented to by?

Answer 24

CD4 T helper cells are presented to by MHC class II
these have an alpha chain and a beta chain
dendritic cells and macrophages have MHC class II

Question 25

What are CD8 CYTOTOXIC cells presented to?

Answer 25

CD8 cytotoxic cells are presented to by MHC class I−these have an alpha chain and a beta 2 microglobulin−all nucleated cells have MHC class I (all cells in the body that have a nucleus)

Question 26

Why are HIV infected individuals prone to developing Kaposi’s sarcoma?

Answer 26

CD4+ cells reduced in number affecting Th cell mediated immune function

Question 27

Why would taking antibiotics result in thrush?

Answer 27

Removal of harmless residual bacteria allowing replication of candida

Question 28

Which of the following statements explains the role of phagocytic cells in stimulating inflammatory responses?

Answer 28

Phagocytes have Toll-like receptors which recognise bacterial lipopolysaccharides stimulating production of inflammatory cytokines

Question 29

How does a phagocyte protect?

Answer 29

Protection from pathogens processing and presentation of antigens (Ag) Disposal of damaged/dying (apoptotic) cells Activation of adaptive immune system Links innate and adaptive immunity

Question 30

What are opsonins?

Answer 30

antibodies (IgG) | proteins of complement system (C3b, C4b)

Question 31

What is antibody structure?

Answer 31

Tetrameric protein with two identical heavy chains and two identical light chains

Question 32

What is the best laboratory based diagnostic strategy for hepatitis A infection?

Answer 32

Presence of IgM antibodies to hepatitis A virus

Question 33

What is MHCI made of?

Answer 33

alpha chain + beta 2-microglobulin

Question 34

What is MHCII made of?

Answer 34

alpha chain + beta chain;

Question 35

What are MHCII cells?

Answer 35

MHC II: antigen presenting cells: dendritic cells | macrophages

Question 36

What are MHCI cells?

Answer 36

all nucleated cells