Immunology - 1 - Intro

Question 1

What is the function of the immune system?

Answer 1

Importance of Immune System:

• Defense against infections
• Defense against tumors
• Recognize & respond to tissue grafts & newly introduced molecules
• Injure cells & induce pathologic inflammation

Immunity

• Resistance to disease
• Response = coordinated rxn of cells & molecules to infectious microbes

Question 2

What are the mechanical, chemical, and microbiological barriers to infection?

Question 3

What is the difference btw innate and adaptive immunity?

Answer 3

Innate immunity

• epithelial barriers
• phagocytes
• dendritic cells
• complement
• NK cells

Adaptive immunity

• B lymphocytes –> Abs
• T lymphocytes –> Effector T cells

Question 4

What is the difference btw humoral and cell-mediated immunity?

Answer 4

Humoral Immunity

• Extracellular microbes
• Responding B lymphocytes
• Effector mechanism –> secreted Abs
• Function:
  
  • block infections & eliminate EXTRACELLULAR microbes

Cell-mediated Immunity

• Phagocytosed microbes in macrophages/Intracellular microbes
  
  • viruses/replication w/in infected cell
• Helper T lymphocyte/Cytotoxic T lymphocyte
• Function:
  
  • Activate macrophages to kill phagocytosed microbes
  • Kill infected cells & eliminate reservoirs of infection

Question 5

What are the phases of an immune response?

Answer 5

1. Recognition phase
   
   • naive B lymphocyte
   • naive T lymphocyte
     
     • proliferation
2. Activation phase –> day 7
   
   • Differentiation
     
     • Ab producing cell
     • Effector T lymphocyte
3. Ag elimination –7-14 days
   
   • humoral immunity
   • cell-mediated immunity
4. Contraction (homeostasis)
   
   • Apoptosis
5. Memory
   
   • Surviving memory cells
   • Secondary immune response