Immunity to Microorganisms-L12

Question 1

Mechanisms of innate immunity

Answer 1

1. Skin
2. pH barriers
3. Flushing
4. Lysozyme–destroys cell walls
5. Phagocytes
6. Complement

Question 2

Staph aureus protein A

Answer 2

Binds to and blocks opsonizing action of IgG

Question 3

Strep pneumonia

Answer 3

Antiphagocytic capsule

Question 4

M protein

Answer 4

Antiphagocytic factor

Question 5

Antibody can:

Answer 5

• Prevent attachment to epithelium (Secreted IgA)
• Trigger complement
• Bind to antiphagocytic M proteins or capsules and act as an opsonin
• Neutralize toxins
• Neutralize spreading factors

Question 6

Facultative intracellular parasites

Answer 6

-Can survive inside the phagosome. Activated macrophages may be able to kill better. TH1 response.

Question 7

Cell mediated immunity is important for:

Answer 7

• Listeria monocytogenes
• Mycobacterium tuberculosis
• Mycobacterium leprae

Question 8

Most important mechanisms in the clearance of parasites

Answer 8

T cell response. Cytotoxic T cells may kill cells infected with parasites. T cells activate macrophages that kill many different parasites.

Question 9

Mechanisms by which parasites escape the immune response

Answer 9

1. Inaccessibility–form cysts or hide in host cells
2. Avoidance of recognition–vary cell surface antigen expression or pick up self antigen
3. Immunosuppression
4. Survive inside macrophages

Question 10

Mechanisms of antiviral immunity

Answer 10

• Antibody–neutralize the virus
• Localized IgA responses
• Ab mediated lysis of virions (with complement)
• Cytotoxic T cells
• Interferons–gamma interferon activates macrophages