Immunity to infection

Question 1

What is the principle protective immune response against bacteria?

Answer 1

specific antibodies that opsonize bacteria for phagocytosis by macrophages and neutrophils

Question 2

What can specific antibody and complement do to gram negative bacteria vs gram positive bacteria?What do specific antibodies do with toxins?

Answer 2

1. gram negative bacteria=lyse

• ex. neisseria meningitidis
• antibody, complement, phagocytosis

2. gram positive bacteria=opsonize
   - ex. streptococcus pneumoniae (antibody to capsule) —require both antibody and complement
   - ex. staphylococcus aureus
3. Neutralize toxins
   ex tetanus toxin

-ex. streptococcus pyogenes

Question 3

How do cells protect against intracellular bacteria?

Answer 3

cell mediated

-Th1–> CD4 cells that activate macrophages by the production of cytokines

Question 4

What is a disease that uses the TMMI response?

Answer 4

Mycobacterium tuberculosis

Question 5

What type of microbes are viruses? How does the immune system respond?

Answer 5

Intracellular

1. Innate immunity against viruses: cytokines and NK cells
2. Adaptive immunity: Specific Cytotoxic T cells
3. Specific antibodies, synthesized prior to T cell mediated killing of infected cells

Question 6

What cells are there at day 2,3,7?

Answer 6

2=neutrophils/mac
3=NK
7=T cell

Question 7

When is IgM present?IgG

Answer 7

IgM-
3-4 days
peaks at 2-3 weeks

IgG
5-7 days
can persist longer

Question 8

What mechanisms combat viral infections but not bacterial infections?

Answer 8

cytotoxic lymphocytes-
natural killer cells
interferons(non virally infected host cells-mechanism:cellular anti-viral state)

Question 9

What happens in diseases caused by exotoxigenic organisms like *clostridium tetani) ?

Answer 9

Eliminate invading organism and neutralize toxin

-if does not block toxin-toxin-blocks inhibitory neuron leading to chronic muscle contraction

Question 10

What are extracellular organisms?

Answer 10

Bacteria
Eukaryotes
-single celled (fungi)
-multicellular (parasites)

Question 11

What are intracellular organisms?

Answer 11

Bacteria
protozoa
viruses

Question 12

What does IgA protect from?

Answer 12

organisms that infect mucosal surfaces

-Neisseria gonorrhea

Question 13

How are fungi taken care of? What is an example of a fungus?

Answer 13

phagocytic cells
-cytokine activated phagocytosis

-Candida albicans

Question 14

Schistosoma mansoni causes infection of the gut, what is the response of the immune system to parasites?

Answer 14

1. antibody directed complement attack
2. Antibody dependent cellular cytotoxicity (ADCC)–>mediated by eosinophils
   - innate immunity is generally ineffective

Question 15

Viruses evoke every form of immunity? What are some ways?

Answer 15

1. enveloped viruses can be damaged by complement
2. phagocytes can take up and destroy antibody and complement coated viruses
3. Infererons, NK cells, antibody, CTL

Question 16

What produce the different interferons?

Answer 16

1. INF-alpha=leukocytes
2. INF-beta=any cell in the body
3. INF-gamma-Th1 cells (type 2) -produced as a cytokine by T cells and activates macrophages to enhanced level of cytotoxicity

Question 17

What type of INF does a leukocyte or fibroblast release?

Answer 17

Type 1 IFN (alpha or beta)
-infuse to the surrounding cell and produce proteins that prevent the synthesis of viral proteins

-antiviral proteins-a synthetase and a protein kinase

Question 18

What two enzymes does interferon synthesize?

Answer 18

1. synthetase
   - catalyzes the polymerization of adenine
   - activates ribonuclease to degrade viral mRNA
2. protein kinase
   - transfers phosphate group to initial factor EIF-2 that is involved in protein synthesis
   - viral mRNA remains untranslated
   - viral mRNA attacked by ribonucleases and degraded