IM1: Cells of the immune system

Question 1

What are the 3 types of granulocytes

Answer 1

1. Neutrophils
2. Eosinophils
3. Basophils

Question 2

What are the functions of neutrophils

Answer 2

Most numerous, phagocytose and ingest bacteria

Question 3

What are the functions of eosinophils

Answer 3

Defence against parasites and involved in allergic reaction

Question 4

What are the functions of basophils

Answer 4

Defence against parasites and involved in allergic reaction

Question 5

What are the functions of mast cells

Answer 5

Mediate allergic reactions through release of histamine

Question 6

What are the functions of macrophages

Answer 6

Found in bloodstream for phagocytosis and antigen presentation

Question 7

What are the functions of dendritic cells

Answer 7

Responsible for phagocytic antigen uptake and presentation to T-cells

Question 8

What are the functions of NK cells

Answer 8

Natural killer cells kill cells infected with intracellular pathogens by releasing lytic granules

Question 9

What are the functions of B cells

Answer 9

• present antigens to T-cells

- produce antibodies

Question 10

What are the three functions of antibodies

Answer 10

1. Neutralisation; surround pathogen and prevent adherence to cells
2. Opsonisation; coat pathogen for marking to promote phagocytosis
3. Complement activation; enhance opsonisation and lysis of bacteria

Question 11

How are antibodies expressed

Answer 11

1. B-cell receptor = BCR on the surface
2. B cells secrete antibodies to diffuse and bind

The antigen is initially recognised by BCR and then activates B cells to secrete antibodies specific to the bacterium

Question 12

What is IgM important for

Answer 12

Complement activation

Question 13

What is IgG important for

Answer 13

Neutralisation, opsonisation and complement activation

Question 14

What is IgA important for

Answer 14

Neutralisation in the GIT

Question 15

What is IgE important for

Answer 15

Activating mast cells in parasitic and allergic responses

Question 16

What is IgD important for

Answer 16

This is the B-cell receptor

Question 17

What is the role of CD8+ T cells

Answer 17

Recognising and removing virus infected cells and cancer cells (CTLs = cytotoxic lymphocytes) they have granules containing cytotoxins causing apoptosis

They are tightly regulated due to their high potency

Question 18

What is the importance of TH1 cells

Answer 18

Coordinating immune responses against intracellular microbes (esp. bacteria) by producing and secreting molecules that alert and activate other immune cells

Question 19

What is the importance of TH2 cells

Answer 19

Coordinate immune responses against extracellular pathogens by alerting B cells, granulocytes and mast cells

Question 20

What is the importance of TH17 cells

Answer 20

Produce IL-17 which activates immune and non-immune cells and is important for neutrophil recruitment

Question 21

What is the importance of T-regs

Answer 21

Prevent adverse immune activation and prevent immune response against self cells

Question 22

What do type I interferons mediate

Answer 22

Antiviral immune response

Question 23

What do type II interferons mediate

Answer 23

Antibacterial response

Question 24

What do interleukins do

Answer 24

Provide instructions with activator or inhibitor responses

Question 25

What is the role of tumour necrosis factor

Answer 25

Stimulates immune-cell proliferation and activation and are important in inflammatory resoisnes; TNF blockers are used to treat autoimmune disease

Question 26

What is the role of toll like receptors

Answer 26

Recognise general microbial patterns and are essential for innate immune-cell activation and inflammatory responses

Question 27

What are B-cell receptors

Answer 27

These are found on the cell surface and are also secreted as antibodies to neutralise pathogens

Question 28

What is the role of major histocompatibility complex (MHC)

Answer 28

MHC proteins are carriers for presenting antigens on cell surfaces

Question 29

What do MHC class I proteins do

Answer 29

Present viral antigens which will be recognised by CD8+ T cells which will recognise and kill the infected cells

Question 30

What do MHC class II proteins do

Answer 30

Only expressed by APC's (dendritic cells and macrophages) and present antigens to CD4+ T cells