Innate to Adaptive Immunity (complete)

Question 1

Define pattern-recognition receptor (PRR)

Answer 1

Proteins on cell surface expressed by cells of the innate immune system

Most cells have these!

They identify PAMPs

Question 2

Define pathogen-associated molecular pattern (PAMP)

Answer 2

Foreign molecular structures on pathogens (e.g. bacterial cell wall protein, bacterial dsRNA)

Recognized by PRRs in innate immune system

Question 3

Define Toll-like receptor (TLR)

Answer 3

Type of PRR

A protein that recognizes a foreign molecular structure that humans don’t have

At least 10 TLRs exist

Question 4

Define damage-associated molecular pattern (DAMP)

Answer 4

Stress or damage indicators expressed by body cells

Question 5

Name common foreign patterns recognized by TLR. (Don’t need to know all details — just general.)

Answer 5

TLR1: lipopeptide -- bacterial 
TLR2: zymosan -- fungal
TLR3: dsRNA -- viral
TLR4: endotoxin/lipopolysaccharide
TLR5: flagellin (bacterial type)
TLR6: lipopeptide (mycoplasma)
TLR7: ssRNA (influenza)
TLR8: ssRNA (viral)
TLR9: unmethylated CpG (herpes virus)
TLR10: asthma connection

Question 6

What is the transcription factor most commonly activated in inflammation?

Answer 6

NK-Kappa B

Question 7

Define cytokine

Answer 7

• Small signaling protein molecules
• Secreted by immune cells
• A large family of regulators

Question 8

Define chemokines

Answer 8

• A type of cytokine
• Have ability to induce directed chemotaxis in nearby responsive cells
• When released, WBCs move closer to them

Question 9

Describe the function of the innate immune response

Answer 9

• Detects intruders
• Arrange for intruder inactivation, destruction, removal
• It’s fast, but can’t adapt to new challenges
• It only sees a few established patterns

Question 10

Name the cell that forms the bridge between innate and adaptive immunity

Answer 10

• Dendritic cells!
• Immature DC: activated by cytokines/chemokines from innate immune system — phagocytic, eat bad stuff
• Mature DCs: leave affected area, travel in lymphatics and show bad thing to T and B cells— look mom! look what I have!

Question 11

Discuss T cells. What are their principle roles in immunity?

Answer 11

• Recognize Ags through surface receptors (scans surface)
• When it sees something, it’s activated
• Then proliferates and daughters travel throughout body — go to where the bad stuff is
• When there, it releases lymphokines — cause inflammatory response, activates/attracts macros

Question 12

Describe some functions of antibodies

Answer 12

• Released by B cells (soluble versions of B cells)
• Protect areas between the cells — ineffective if the Ag is already in the cell
• Bind to free floating Ag – maybe enough to neutralize the Ag or just prevent its binding to a target cell
• Then are phagocytosed

Question 13

Give examples of immunopathology

Answer 13

1) Type I: immediate hypersensitivity (allergies)
2) Type II: autoimmunity due to Abs that attack self
3) Type III: Ab-Ag complex gets trapped in basement membrane — causes problems
4) Type IV: T-cell mediated — innocent bystander injury (think TB, CTL go overboard and destroy lung tissue)
5) Chronic frustrated immune response: Ag is not self, just something you can’t get rid of (celiac) — it’s a chronic battle (unless you stop eating gluten)
6) HIV/AIDS: infects Th cells by binding to CD4 surface molecules, retrovirus —» progressive loss of Th cells

Question 14

What is “humoral” (antibody-mediated) immunity? (include: types of lymphocytes involved, nature of molecules they release when activated)

Answer 14

• Think B cells
• B cells release soluble versions of themselves (Abs)
• they do their job: attract macros/inactivate Ag/prevent it from binding to target cell

Question 15

What is cell-mediated immunity? (include: types of lymphocytes involved, nature of molecules they release when activated)

Answer 15

• Think T cells
• T cells just duplicate rapidly when activated by DC
• Leave the node, travel to affected area
• Attract/activate macros to ATTACK