Adaptive Immunity 1

Question 1

What is the cellular and humoral components of adaptive immunity?

Answer 1

T cells - cellular
B cells - humoral

Question 2

When is the adaptive immunity activated?

Answer 2

after 4-7 days

Question 3

What does the threshold level mean?

Answer 3

the amount of pathogen present to mediate an immune response

Question 4

What are the the 3 main receptors of the adaptive immune response?

Answer 4

T cell receptor
B cell receptor
Major Histocompatibility Complex (MHC)

Question 5

What is the difference between the innate receptors (TLR) and adaptive receptors?

Answer 5

innate receptors cannot change shape to identify different antigens

adaptive receptors can rearrange structure depending to gene expression of each protein subunit.

Question 6

How do T cells recognise peptides?

Answer 6

via TCR and MHC interations

Question 7

Where do T cells mature?

Answer 7

thymus

Question 8

What does Tregs balance?

Answer 8

pro- and anti- inflammatory responses
they dampen down immune responses

Question 9

What are the subsets of T cells?

Answer 9

CD4+
CD8+
Tregs

Question 10

What is the receptor for CD8+ and what does it bind to?

Answer 10

CD8
MHC 1

Question 11

What is the role of MHC 1?

Answer 11

alerting the immune system to virally infected cells.

Question 12

What is the receptor for CD4+ and what does it bind to?

Answer 12

CD4
MHC 2

Question 13

What is the role of MHC 2?

Answer 13

for APCs presenting antigens from microbes such as bacteria, fungi etc.

Question 14

What is the receptor involved in the activation of both CD4+ and CD8+?

Answer 14

CD3

Question 15

What are the two classes of T cell receptor?

Answer 15

Alpha
Beta

Question 16

What classes of T cell receptor do a small portion (around 5%) of T cells express?

Answer 16

Gamma
Delta

Question 17

What are the two regions of the chains?

Answer 17

Constant
Variable (changing)

Question 18

What are the 3 gene segments of the variable region and what do they encode?

Answer 18

V (variable) (both α and β chains)
D (diversity) (β chain only)
J (joining) (both α and β chains)

Question 19

By what process are genes rearranged to identify new pathogens?

Answer 19

somatic recombination

Question 20

What is somatic recombination driven by?

Answer 20

RAG (recombinase enzymes)

Question 21

What do T cells interact with in the thymus?

Answer 21

pass by thymic cortical epithelial cells and interact

Question 22

Describe the two processes of thymic education

Answer 22

Positive selection - if cells cannot recognise self-peptides, they die. if they do they move to negative selection

Negative selection - if cells bind too strongly to self-peptides, they die

Question 23

Where do T cells immigrate to after education?

Answer 23

circulating blood
lymph nodes
lymphatics

Question 24

What do the three signals do to the T cell?

Answer 24

signal one = activation of T cell
signal two = survival and clonal expansion of T cell
signal three = differentiation into subsets of effector T cells (specifically for CD4+ helper T cells)

Question 25

What are the three signals that prime T cells?

Answer 25

1’ MHC-TCR interaction 2’ co-stimulatory molecules interactions (CD80/CD86 and CD40 on DC ---- CD40L and CD28 on T cell) 3’ signal dictates what T helper cell the naïve cell becomes.

Question 26

What is signal 1 but no signal 2 known as?

Answer 26

anergy

Question 27

What does the third signal lead to in CD8+ cells?

Answer 27

the third signal leads to effector function e.g., production of enzymes for degradation

Question 28

What enzymes induce target cell apoptosis?

Answer 28

perforin granzyme

Question 29

What does interferon-γ do?

Answer 29

instructs immune cells such as macrophages and cytotoxic T cells to destroy infected cells.

Question 30

What is the role of TH1 cells?

Answer 30

Main role in supporting macrophage function Source of interferon-γ

Question 31

What is the role of TH2?

Answer 31

Supporting plasma B cell responses and allergic reactions - activates mast cells and eosinophils Source of IL-4, IL-5 and IL-6

Question 32

What do IL-4, IL-5 and IL-6 do?

Answer 32

instructs B cells to produce antibodies

Question 33

What is the role of TH17?

Answer 33

Main role in supporting innate immune responses Enhances clearance of extracellular bacteria and fungi Produces IL-17 and IL-22

Question 34

What does interleukin-17 do?

Answer 34

stimulate epithelial cells to produce antimicrobial peptides

Question 35

What is the role of TFH?

Answer 35

T follicular helper cells are found in secondary lymphoid organs in B cell zone (not T cell zone) Work together with B cells for antibody production Produces IL-21

Question 36

What does interleukin-21 do?

Answer 36

drives B cell proliferation

Question 37

What is the role of Treg cells?

Answer 37

Regulatory T cells that function in immune suppression Release inhibitory cytokines IL-10 Inhibit T cell activation and dendritic cell activation

Question 38

What is the role of CD8+ cells?

Answer 38

Activation arises from interactions between MHCI and TCR Induce host cells to undergo apoptosis (programmed cell death) Produces enzymes such as granzyme/perforin

Question 39

What does loss of TFH cells mean?

Answer 39

loss of T follicular helper cells leads to dysfunctional antibody production in germinal centre of lymph nodes