Immune cell profiles

Question 1

Macrophages

Answer 1

• One of the first cells that a pathogen is likely to encounter
• Characterised by circular nucleus with some cytoplasmic space
• Can be fixed or patrolling/wandering
• Role: Recognition of pathogen + elimination of pathogens/dead/damaged cells/ cell signalling
• Depending on where they are located, they have different names

Question 2

Dust cells

Answer 2

Alveolar macrophages located in the pulmonary alveolus of the lungs

Question 3

Histocytes

Answer 3

Specialist Macrophages located within the connective tissues

Question 4

Kupffer cells

Answer 4

Specialist Macrophages located within the liver

Question 5

Microglia

Answer 5

Specialist Macrophages found in neuronal tissue

Question 6

Epitheloid cells

Answer 6

Specialist Macrophages found in granulomas

Question 7

Osteoclasts

Answer 7

Specialist Macrophages found in the bone

Question 8

Sinusoidal lining cells

Answer 8

Specialist Macrophages found in the spleen

Question 9

Mesangial cells

Answer 9

Specialist Macrophages found in the kidney

Question 10

Neutrophils

Answer 10

• A type of granulocyte with a lifespan of 2-3 days, characterised by multi-lobed nuclei
• Has Primary + Secondary granules that act as antimicrobials
• Can also phagocytose + often attracted by chemotaxic factors
• Role: To kill

Question 11

Primary granules

Answer 11

• Contains a variety of enzymes that aid in killing pathogens ie peroxidase, lysozyme + other hydrolytic enzymes

Question 12

Secondary granules

Answer 12

• Contains chemicals or enzymes that can have regulatory functions or continue to assist in immune responses ie collagenase, lactoferrin, lysozyme

Question 13

Dendritic cells

Answer 13

• Role: Potent antigen presentation in lymph nodes, activating the adaptive immune response
• Found in most tissues
• Can be derived from circulating monocytes

Question 14

Eosinophils

Answer 14

• Motile phagocytic + granular cells that circulate in blood + can migrate into tissue spaces
• Characterised by a bi-lobed nucleus + granulated cytoplasm + stained red by eosin dye
• Role: Phagocyte that plays role in host defence against parasites as secreted contents of granules that may damage parasitic membranes

Question 15

Basophils

Answer 15

• Role: Non-phagocytic granulocyte that mediates certain allergenic sequences
• Characterised by lobed nucleus + heavily granulated cytoplasm
• Releases pharmacologically-active substances ie histamine from their granules that play a major role in certain allergenic response

Question 16

Mast cells

Answer 16

• Found in most tissues
• 2 different types:
  + Mucosal mast cells in gut
  + Connective tissue mast cells
• Role: Mediator of a variety of allergic inflammatory conditions. When activated, they can increase vascular permeability, vasodilation, smooth muscle cell contraction + attract neutrophils to inflammatory site
• Activated by multiple exposures + bindings to allergen

Question 17

B cells/Plasma cells

Answer 17

• Role: When activated, they differentiate into plasma cells to produce antigen-specific antibodies
• They express:
  + Surface antibody (BCR)
  + CD19 (Co-receptor)
  + MHC-2 molecules
  + CD40
• Activated form characterised by
  + Extensive RER + Golgi apparatus
  + Plasma cells have lower levels of membrane bound Ab

Question 18

T helper cells

Answer 18

• Role: To help other immune cells become fully functional

- Characterised by CD4 expression, strict recognition + activation by antigen-class 2 MHC complex