Cells of the immune system

Question 1

Cells of the innate immune response?

Answer 1

neutrophils
macrophages
Natural Killer Cells
Dendritic cells

Question 2

Role of Neutrophils?

Answer 2

• Defend against all acute infections as the main phagocytic cells.
• Also antigen-presenting

Question 3

Appearance of Neutrophils?

Answer 3

• segmented nulcei

- purple granules in the cytoplasm

Question 4

Role of tissue macrophages?

Answer 4

-Phagocytosis of pathogens, debris and dead tissue cells

Question 5

Tissue-specific types of macrophages?

Answer 5

Kupffer cells (liver)
Alveolar macrophages
Osteoclasts (bone)
Microglial cells (neurons)

Question 6

Function of Dendritic cells?

Answer 6

-Main antigen-presenting cell type

Question 7

Role of circulating monocytes?

Answer 7

Travel to target tissues via bloodstreat, where they differentiate into macrophages.

Question 8

Appearance of monocytes?

Answer 8

Horseshoe nuclei.

Question 9

Role of basophils?

Answer 9

• Circulating counterparts of mast cells

- Allergic reactions, inflammation and parasitic infection

Question 10

Appearance of basophils?

Answer 10

Bilobed nuclei

Large purple-stained granules (contain histamine and heparin)

Question 11

Role of mast cells?

Answer 11

Tissue cells

• allergic reactions
• inflammation
• parasitic infections

Question 12

Role of Eosinophils?

Answer 12

1. Defend against worms and helminths.

2. Involved in IgE-mediated allergic reactions (asthma)

Question 13

Appearance of eosinophils?

Answer 13

bilobed nuclei

red-staining granules

Question 14

Appearance of lymphocytes (B and T cells)?

Answer 14

Small cells with large round nuclei and NO granules

Question 15

Function of IgM?

Answer 15

1. First Ig produced in response to antigen.
2. Pentameric IgM fixes complement
3. Monomeric IgM acs as antigen receptor on B cells.

Question 16

Function of IgG?

Answer 16

1. Fixes complement
2. Crosses placenta into faetal circulation
3. Main Ig produced

Question 17

IgA function?

Answer 17

-dimeric IgA is found in mucous, tears, saliva and breast milk

Question 18

IgE function?

Answer 18

• Antiparasitic and allergic responses

- Fc of IgE binds to mast cells and basophils causing degranulation

Question 19

IgD cell function?

Answer 19

Antigen receptors on B cells

Question 20

Role of Th1 cells?

Answer 20

1. Cause activation of Cytotoxic T-cells by activating antigen-presenting cells.
2. This aids the destruction of phagocytosed pathogen.

Question 21

What signals do Th1 cells use to activate antigen-presenting cells?

Answer 21

INF-gamma and CD40 ligands

Question 22

How do Antigen-presenting cells activate Cytotoxic CD8+ cells?

Answer 22

1. Present antigen on MHC I

2. Provide second signal (e.g. B7)

Question 23

What do activated Cytotoxic CD8+ cells do?

Answer 23

Kill infected cells

Question 24

What’s the CD8+ cells’ killing mechanism?

Answer 24

-Perforate bacterial cell wall with Perforin and induce apoptosis

Question 25

What do CD8+ cells do to virally-infected cells?

Answer 25

Block viral replication with INF-gamma.

Question 26

How do cytotoxic CD8+ T cells recohgnise infected cells?

Answer 26

Via antigen displayed on their surface MHC I

Question 27

What is the role of the Natural Killer cells?

Answer 27

Destroy virally infected and cancer cells.

Question 28

How do NK cells recognise infected / cancer cells?

Answer 28

They target cells lacking surface MHC I