Infection - Adaptive Immune Response

Question 1

Give some features of antigen presenting cells

Answer 1

• strategically located (skin, mucous membranes, lymphoid organs, blood circulation)
• pathogen capture (phagocytosis and macropinocytosis of soluble particles)
• diversity in pathogen sensors (can sense both extracellular and intracellular pathogens)

Question 2

Where are dendritic cells found?

Answer 2

Lymph nodes, mucous membranes and blood

Question 3

What do dendritic cells present antigens to?

Answer 3

Naive T-cells

Question 4

Where are Lagerhans cells found?

Answer 4

Skin

Question 5

What do Langerhans cells present antigens to?

Answer 5

Naive T cells

Question 6

Where are macrophages found?

Answer 6

Various tissues

Question 7

What do macrophages present antigens to?

Answer 7

Effector T cells

Question 8

Where are B cells found?

Answer 8

Lymphoid tissues

Question 9

What do B cells present antigens to?

Answer 9

Effector T cells and naive T cells

Question 10

What are major histocompatibility complexes?

Answer 10

They hold the antigens that are presented to T cells

Question 11

True or false - MHCs are only used in humoral immunity?

Answer 11

False - they are used in both humoral and cell-dependent immunity

Question 12

What sort of MHC are HLA-A, HLA-B and HLA-C?

Answer 12

They are all class 1 molecules, found on all nucleated cells

Question 13

What are HLA-DR, HLA-DQ and HLA-DP all examples of?

Answer 13

Class II molecules, found on dendritic cells, macrophages and B cells

Question 14

Which type of MHC molecules present to intracellular pathogens?

Answer 14

Class I

Question 15

What type of MHC molecule present to extracellular molecules?

Answer 15

Class II molecules

Question 16

Give some key features of MHC class I and II molecules

Answer 16

• co-dominant expression (both parental genes expressed, meaning increased number of different MHC molecules)
• polymorphic genes (different alleles in different individuals increase presentation of different antigens)

Question 17

What are intracellular microbes?

Answer 17

Viruses, some bacteria, protozoa

Question 18

What are extracellular microbes?

Answer 18

Bacteria, parasites, worms, fungi

Question 19

Where are T cells matured?

Answer 19

In the thymus

Question 20

True or false - there are two types of CD4 cell that can be activated to counter extracellular microbes

Answer 20

True - TH2 and TH17. There is only one which can work against intracellular microbes - TH1

Question 21

What are the roles of TH1 CD4+ cells?

Answer 21

• activate CD8 which activate cytotoxic T lymphocytes, which target infected cells via perforins and granzymes
• activate B cells which produce antibodies
• activate macrophages which work with antibodies to kill opsonised microbes

Question 22

What are the roles of TH2 CD4+ cells?

Answer 22

• activate eosinophils which kill parasites
• activate B cells which produce antibodies
• activate mast cells which cause local inflammation and allergies

Question 23

What is the role of TH17 cells?

Answer 23

Produce neutrophils which phagocytose other molecules

Question 24

What is the difference between the primary and secondary antibody response?

Answer 24

Primary - mostly IgM produced, IgG builds up
Secondary - on secondary infection, less IgM is produced and far more IgG is made, which causes the secondary response to be faster, stronger, have a longer duration and a higher affinity.

Question 25

What are the functions of IgG?

Answer 25

- Fc-dependent phagocytosis - complement activation - neonatal immunity - toxin/virus neutralisation

Question 26

What are the functions of IgA?

Answer 26

Mucosal immunity

Question 27

What are the functions of IgM?

Answer 27

Complement activation

Question 28

What are the functions of IgE?

Answer 28

- Immunity against helminths | - mast cell degranulation

Question 29

Are extracellular microbes attacked by humoral or cell-dependent immunity?

Answer 29

Extracellular microbes - humoral immunity | Intracellular microbes - cell-dependent immunity