Lecture 9 - Adaptive Immune Response (Recognition)

Question 1

What does the suffix -mab mean?

Answer 1

Monoclonal antibody

Question 2

What is a pathogen?

Answer 2

Any microorganisms that can cause disease in humans?

Question 3

What is a Naive T cell?

Answer 3

T cells that have not yet encountered the antigen of a pathogen

Question 4

What is the only cell that can activate T cells?

Answer 4

APCs (Antigen presenting cells)

Question 5

How do APCs give information to T cells?

Answer 5

Sense the pathogen
Capture the pathogen
Process the pathogen
Present the pathogens antigen to T cells

Question 6

What are the 4 different APCs?

Answer 6

Dendritic cells
Langerhans cells
Macrophages
B cells

Question 7

What is the similarity between Dendritic cells and Langerhans cells?

Answer 7

Langerhans are just Dendritic cells that are present in the skin

Question 8

What do dendritic cells and langerhans cells present antigens/pathogens to?

Answer 8

Naive T cells

Question 9

What cells do Macrophages and B cells present pathogens/antigens to?

Answer 9

Effector T cells

Question 10

What is the function of Dendritic cells and langerhans cells presenting pathogens to Naive T cells?

Answer 10

To stimulate T cell response against most pathogens

Question 11

What is the T cell response?

Answer 11

T helper cells (help B cells)
Cytotoxic T cells

Question 12

What is the function of Macrophages presenting pathogens to Effector T cells?

Answer 12

Produce cytokines which promotes phagocytise activities

Question 13

What is the function of B cells presenting pathogens to effector (helper) T cells?

Answer 13

To stimulate the Antibody response (Humoral response)
Aim to produce the best antibody IgG

Question 14

What are effector T cells?

Answer 14

T cells that have previously encountered the antigen and are capable of performing effector functions during an immune response

Question 15

What is the largest lymphoid organ in the body?

Answer 15

Spleen

Question 16

What are the 3 key features of APCs?

Answer 16

Strategic location

Diversity in pathogen capture mechanism (Phagocytosis + macropinocytosis)

Diversity in pathogen sensors (PRRs)

Question 17

What do the PRRs of APCs bind to on pathogens?

Answer 17

PAMPs

Question 18

What type of receptors are often PRRs to detect pathogens?

Answer 18

Toll like receptors

Question 19

Where can toll like receptors be found?

Answer 19

On plasma membrane of the cell (extracellular pathogen detection)

Nuclear membrane (intracellular pathogen detection)

Question 20

What toll like receptor typically binds to Staphylococcus aureus?

Answer 20

TLR2
Since it’s Gram +ve

Question 21

What pathogen associated molecules bind to TLR4?

Answer 21

Lipopolysaccharides
E.g made by Neisseria meningitidis or E.coli
Gram Negative

Question 22

What does binding of endotoxins (Lipopolysaccharides) to TLR4 activate?

Answer 22

Innate immunity
Inflammatory response

Question 23

What happens to the APCs once its captured and processed the pathogen?

Answer 23

Migrates to lymphoid tissue to activate the maximum amount of T and B cells as possible

Question 24

What are a few examples of lymphoid tissues?

Answer 24

GALT (In Gut)
BALT (In Bronchioles of lungs)
SALT (In Skin)

Lymph nodes
Spleen

Question 25

What happens to the APCs once they’ve migrated to the lymphoid tissue?

Answer 25

Present antigens to correct T cells that lead to the best adaptive immune response

Question 26

What adaptive immune response is stimulated when exposed to extracellular microbes?

Answer 26

Humoral Immunity (Antibody production)

Question 27

What adaptive immune response is stimulated when exposed to intracellular microbes?

Answer 27

Cell mediated immunity (Cytotoxic T cell response)

Question 28

What is the function of Cytotoxic T cells?

Answer 28

Destroys infected cells (E.g cells infected by a virus)

Question 29

What do Intracellular microbes usually produce that stimulate natural killer cells?

Answer 29

Interferons

Question 30

What is the importance of APCs?

Answer 30

In infection by Intracellular or extracellular they present pathogens to Naive T cells activating the best immune response (Humoral immunity or cell mediated immunity)

Question 31

How are pathogens presented to naive T cells?

Answer 31

Via MHCs (Major Histocompatibility Complex) also called HLA (Human Leukocyte Antigen) MHC = HLA

Question 32

What are the 2 types of MHC molecules?

Answer 32

MHC Class I MCH Class II

Question 33

What cells express MHC Class I molecules?

Answer 33

ALL Nucleated cells

Question 34

What cells express MHC Class II molecules?

Answer 34

Antigen-presenting cells (Dendritic cells, macrophages and B cells)

Question 35

What class of MHC molecules do Dendritic cells have?

Answer 35

Both MHC Class I and Class II Is both a nucleated cell and an antigen presenting cell

Question 36

What class of MHC molecules do red blood cells have?

Answer 36

Neither since they are not nucleated (no Class I) or Antigen presenting cells (no Class II)

Question 37

What type of microbes, (intracellular or extracellular) are always presented by MHC Class I molecules?

Answer 37

Intracellular microbes

Question 38

What type of microbes, (intracellular or extracellular) are always presented by MHC Class II molecules?

Answer 38

Extracellular microbes

Question 39

What is the advantage of their being different alleles for MHC molecule production?

Answer 39

Means different people can respond to different microbes

Question 40

What T cells will recognise MHC Class I molecules?

Answer 40

CD8 positive T cells

Question 41

What T cells will recognise MHC Class II molecules?

Answer 41

CD4 positive T cells

Question 42

When invaded by extracellular microbes, what class of MHC molecule on the APC presents it to the Naive T cell? What molecules will these T cells have?

Answer 42

MHC Class II CD4 positive Naive T cells

Question 43

When invaded by intracellular microbes, what class of MHC molecule on the APC presents it to the Naive T cell? What molecules will these T cells have?

Answer 43

MHC Class I molecules CD8 positive Naive T cells

Question 44

What Naive T cells are responsible for triggering Cell-mediated/cytotoxic T cell response?

Answer 44

CD8+ T cells

Question 45

What is the exogenous pathway/processing of extracellular microbes?

Answer 45

Microbes captured via phagocytosis or macropiniocytosis Degraded in endosome Vesicle containing MHC Class II complex fuses witht endosome APCs present these antigens to CD4+ T cells

Question 46

What is the endogenous pathway/processing of intracellular microbes?

Answer 46

Viral protein in the cytosol Proteasome marks it for destruction Broken down antigenic peptide transported to the ER Peptide exposed to MHC Class I Complex displays the viral antigen to CD8+ T cells

Question 47

Why is it good that there is genetic polymorphism for MHC molecules?

Answer 47

No 2 individuals have same set of MHC molecules so a single microbe is unlikely to wipe everybody out More diversity of MHC molecules means more likely to develop immunity to a disease

Question 48

If a patient with HIV has low CD4+ T cell count and a high viral load, what treatment would you do?

Answer 48

Anti-retro viral Therapy

Question 49

If a patient with HIV had a High CD4+ T cell count and a low viral load, what would you do?

Answer 49

Nothing

Question 50

Why is it important that the HLA molecules (MHC) between an organ donor and recipient match?

Answer 50

Rejection

Question 51

What autoimmune diseases are associated with the presence of certain HLA molecules?

Answer 51

Ankylosis spondylitis Insuli-dependant Diabetes Mellitus SLE (Systemic Lupus Erythromatosus)

Question 52

Is a patient more or less susceptible to suffering to an infection if they have a low MHC molecule diversity?

Answer 52

More susceptible