Immunology 2

Question 1

Immune effector cell types:

Answer 1

• All of the cells from our immune system are all derived from a common cell known as the pluripotent progenitor cell (pluripotent- can generate lots of different types of cell)
• Leukocytes refer to all white blood cells
• Granulocytes- cells of the innate immune response
• Lymphocytes – adaptive + innate immune response cells

When stem cells (pluripotent) cells, they can either divide and remain as stem cells, or they could differentiate (this means we can retain our stem cell population for our entire lives

Question 2

The first differentiation step:

Answer 2

• Divide into a common lymphoid progenitor
  
  • Gives rise to B/T/NK (Natural killer) cells
• Divide into a common myeloid progenitor
  
  • Gives rise to all types of granulocyte cells (have a very granular cytoplasm)
  • Also gives rise to mast cells +macrophages
• As the first differentiate step occurs, the cells become committed to that particular linage (they cannot become undifferentiated)

Question 3

The different types of cells:

Answer 3

• Myeloid cells – Innate immune response
• Lymphoid cells – Adaptive immune response (However NK lymphocytes are considered to be part of the innate immune system)
• Exceptions:
  
  • NK lymphocytes are considered to be part of the innate immune system
  • Dendritic cells can be derived from both the lymphoid and myeloid progenitor (ancestor from which something is derived from)

Question 4

What are Monocytes, where are they located and what are their functions?

Answer 4

Monocytes mature into macrophages (monocyte - macrophage)

Location:

• Immature monocytes are found circulating in the blood
• Mature macrophages are found in most tissue + submucosal layers

Functions:

• Act as the first responders in the immune response
• Have a relatively long lifespan
• Act as phagocytes
• Engulf and kill pathogens
• Engulf and kill cell debris
• Have bactericidal activity /
• Act as antigen presenters to T cells
• Activate other immune cells
• Induce inflammation

Question 5

What three types of Granulocytes (Neutrophils) are there and where are they located?

Answer 5

1. Neutrophils
2. Eosinophils – act as anti parasitic
3. Basophils – act as anti parasitic

Granulocytes are also known as polymorphonuclear leukocytes (have lobed appearance as they contain more than one nuclei)

Location:

• Blood, Migrate to infection
• Function:
• Phagocytic (engulf pathogens)
• Bactericidal
• Numerous
• Short lifespan

Question 6

What is the location and functions of dendrite cells?

Answer 6

Location:

• Immature DC are found under the surface of epithelium and in solid organs
• After the uptake of antigens, they migrate via lymphatic’s system to lymph nodes and mature

Function:

• They are phagocytic, they also take up and sample the extracellular location around them in a process of Macropinocytosis
• They phagocytise bacteria to take up antigens and present them to the adaptive arm
• They activate cells of the adaptive arm

Question 7

What are the following for natural killer cells:

1. Location
2. Functions
3. Recognition and phagocytosis:

Answer 7

Location:

• Blood
• They migrate to infected tissue
• Have anti tumour activity

Functions:

• Are lymphocytes but considered to be within the innate arm
• Extracellular release of cytotoxic granules (act as anti viral/anti tumour), NK cells don’t act to engulf pathogens, only to release cytotoxic granules onto them

Recognition and phagocytosis:

• How do phagocytes recognise what they need to engulf?
• They do this by using receptors on the surface of phagocytic cells
• There are different types of receptors that recognise different types of structures