USMLE: IMMUNOLOGY, LFG

Question 1

What is a pathogen-associated molecular pattern (PAMP) and what does it do?

Answer 1

Sequences capable of triggering an immune response. Ex. dsRNA (only found in viruses, never humans), peptidoglycan in G+ bac, endotoxins (lipopolysaccharides) in G- bac, mannose on yeast and fungi…etc.

Question 2

What are microglia, kupffer cells, and osteoclasts all examples of?

Answer 2

macrophages

Question 3

What are the 3 parts of the innate immune system?

Answer 3

1. Phagocytes: Neutrophils and macrophages
2. Complement proteins
3. Natural Killer (NK) cells

Question 4

Which interleukins are secreted by macrophages?

Answer 4

most importantly: IL-1 and TNFalpha

also: IL-6, IL-8, IL-12

Question 5

Why is IL-2 often used to treat certain cancers?

Answer 5

by stimulating CD8 T cells and NK cells attack cancer cells.

note: IL-2 also activates CD4 T cells
* IL-2 does NOT have apoptotic effects
* IL-2 does not inhibit vascular endothelial-derived growth factor (VEGF)

Question 6

What are the 2 major mediators of inflammation circulating in the blood during acute cellulitis?

Answer 6

IL-1 acts on hypothalamus to increase body temperature and cause fever (natural pyrogenic effect).

note: prostaglandin E2 is produced in hypothalamus in response to IL-1, IL-6, and TNF-a BUT it stays there, it never circulates systemically

TNF-a causes vascular leak leading to edema

Question 7

What are acute phase reactants?

Answer 7

Simply, they are proteins whose levels rise when there is inflammation present.

examples: C-reactive protein, fibrinogen
note: erythrocyte sedimentation rate rises as levels of acute phase reactants rise

IL-6 stimulates high acute phase reactants

Question 8

How does MHC-1 clear viral cells?

Answer 8

CD8+ T cells recognize MHC-1 on viral cells and trigger apoptosis.

Question 9

What is the most common leukocyte?

Answer 9

Neutrophils = ~50%

Question 10

Granulocytes

Answer 10

Basophils
Eosinophils
Neutrophils
Mast cells

Question 11

What is petachiae?

Answer 11

circular, non-raised patches that appear on the skin or in a mucous or serous membrane. They occur as the result of bleeding under the skin.

Question 12

True or False: Coagulation factors circulate inactively as “zymogens”.

Answer 12

True.

Question 13

what type of molecule do most coagulation factors become?

Answer 13

“serine proteases”.

A protease cleaves proteins, so, once activated, these guys cleave proteins…and they contain serine.