Immunology - 2 - Cells & Tissue

Question 1

What are the different types of immune cells?

Answer 1

1. Macrophage
   
   • phagocytosis & activation of bactericidal mechanisms
   • Ag presentation
     
     • Derive = Monocyte
2. Dendritic Cell (most potent)
   
   • Ag uptake in peripheral sites
   • Ag presentation
     
     • Derive = pre-dendritic cell
3. Neutrophil (1st on site!)
   
   • Phagocytosis & activation of bactericidal mechanisms
     
     • Derive = Myeloblasts
4. Eosinophil (pink)
   
   • Killing of Ab-coated parasite
5. Basophil (purple)
   
   • Unknown action…maybe allergic rxn?
6. Mast cell
   
   • release of granules containing histamine & active agents
7. Natural Killer Cell
   
   • releases lytic granules that kill some virus-infected cells
8. Lymphocytes
   
   • B = humoral immunity
   • T = cell-mediated

Question 2

What is the importance of central and peripheral lymphoid tissues?

Answer 2

Central lympoid tissue

• bone marrow
• where immature B & T cells are made
  
  • B = mature in bone marrow
  • T = mature in thymus

–> travel thru lymph/bood <—

• immature B lymphocytes
• mature naive T lymphocytes

Peripheral lymphoid organs

• Lymph nodes/Spleen/Mucosal & cutaneous lymphoid tissue
  
  • MALT
• Mature B lymphocytes
• Mature T lymphocytes

Question 3

Diagram the lymph node as an immunologic tissue

Answer 3

1. afferent lymph vessel
2. cortical sinus
3. primary lymphoid follicle (mostly B)
4. secondary lymphoid follicle w/ germinal center
5. paracortical area (mostly T)
6. medullarycords (macrophages + plasma cells)
7. medullary sinus
8. efferent lymph vessel

Question 4

Outline the process of migration of antigens and leukocytes to and from the lymph node.

Answer 4

Lynphocyte Activation

1. naive T/B cells enter via afferent lymph
2. collection of Ags from tussues enter via lymph
3. activation of lymphocytes & initiation of adaptive immune response
4. effector T lymphocytes & Abs leave lymph node via efferent lymph
5. migration of effector cells & blood delivery of Abs to site of infection
6. colletion of Ags enter blood –> spleen
7. add’l activation of lymphocytes & initiation of adaptive immune response

TAKE AWAY: Ag presentation & initiation of ADAPTIVE IMMUNITY occurs in a SECONDARY peripheral organ