Adaptive Immunity 1

Question 1

what does the adaptive immune response consist of?

Answer 1

cell-mediated responses and antibody (humoral) responses

Question 2

what do T cells do in adaptive immunity?

Answer 2

drive cell-mediated immunity

Question 3

what cells does cell mediated immunity involve?

Answer 3

macrophages, natural killer cells, antigen-specific cytotoxic T-lymphocytes

Question 4

what do B cells do in adaptive immunity?

Answer 4

produce antibodies and drive humoral immunity

Question 5

what is a key feature of the adaptive immune system?

Answer 5

immunological memory

Question 6

what is immunological memory?

Answer 6

each pathogen is remembered by a signature T cell and/or B cell receptor

Question 7

what are the stages of adaptive immunity after infection?

Answer 7

transport of antigen to lymphoid organs, recognition by naive B and T cells, clonal expansion and differentiation to effector cells, removal of infectious agent

Question 8

what is the threshold level of antigen?

Answer 8

amount of a pathogen present to mediate an immune response

Question 9

why is the threshold level of antigen important?

Answer 9

the immune system does not need to mediate adaptive immunity if only a small amount of antigen is present as the innate immune system can clear the threat without the help of adaptive

Question 10

what are the three main receptors in adaptive immunity?

Answer 10

T cell receptor (TCR), B cell receptor (immunoglobulins), major histocompatibility complex (MHC proteins)

Question 11

what do multiple genes encoding allow?

Answer 11

the development of a repertoire of receptors with wide specificity

Question 12

what is the difference between innate and adaptive receptors?

Answer 12

innate receptors (TLRs) DON’T have potential to rearrange and change shape to recognise different antigens whereas adaptive receptors CAN rearrange structure depending on gene expression of each protein subunit

Question 13

where are T cells derived from?

Answer 13

bone marrow

Question 14

where do T cells mature?

Answer 14

thymus

Question 15

what do T cells give rise to?

Answer 15

cellular immunity

Question 16

how do T cells recognise peptides?

Answer 16

through the T cell receptors

Question 17

what does T cell repertoire mean?

Answer 17

diversity in TCR (can respond to numerous antigens)

Question 18

what is thymic education?

Answer 18

checkpoints that are in place to ensure T cells only respond to foreign pathogens and not self peptides

Question 19

what do T helper cells (CD4+) do?

Answer 19

function to hep support other immune cells to fight threats

Question 20

what do cytotoxic cells (CD8+) do?

Answer 20

destroy our own cells which have become infected (usually virus-related)

Question 21

what do regulatory T cells (Tregs) do?

Answer 21

regulate or suppress other cells in the immune system

Question 22

what do all T cells start as?

Answer 22

naive T cells

Question 23

what are the 3 types of T cell that naive T cells differentiate into?

Answer 23

T helper cells, cytotoxic cells, regulatory T cells

Question 24

what are Tregs essential in?

Answer 24

trying to balance the homeostasis between pro- and anti- inflammatory responses

Question 25

what is CD8?

Answer 25

a co-receptor that binds to MHC I

Question 26

what is CD4?

Answer 26

a co-receptor that binds to MHC II

Question 27

what is CD3?

Answer 27

a co-receptor involved in activation of both CD4+ and CD8+ T cells

Question 28

what is MHC I usually expressed by?

Answer 28

virally infected cells

Question 29

what is MHC II found on?

Answer 29

just found on antigen presenting cells

Question 30

what are the different chains found on T cell receptors?

Answer 30

alpha and beta chains but a small portion express gamma and delta chains instead

Question 31

what are the two regions of the alpha and beta chains?

Answer 31

constant and variable

Question 32

what are the three genes that encode the variable region of alpha and beta chains of T cell receptors?

Answer 32

V (variable), D (diversity) and J (joining)

Question 33

what is the alpha chain of T cell receptors encoded by?

Answer 33

two gene segments - V and J

Question 34

what is the beta chain of T cell receptors encoded by?

Answer 34

three segments - V, D and J

Question 35

how are genes rearranged?

Answer 35

by somatic recombination

Question 36

what is somatic recombination driven by?

Answer 36

RAG (recombinase) enzymes

Question 37

what does recombination lead to?

Answer 37

different receptor structures that can recognise different antigens

Question 38

what are pre-thymic T cells?

Answer 38

undifferentiated lymphocytes

Question 39

what are the two different types of selection?

Answer 39

positive and negative selection

Question 40

what type of cells do T cells interact with in the thymus?

Answer 40

cortical epithelial cells

Question 41

what is positive selection?

Answer 41

no recognition

Question 42

what is negative selection?

Answer 42

recognition of self antigen

Question 43

where are receptors rearranged?

Answer 43

in the thymus

Question 44

where do positively and negatively selected CD4/CD8+ T cells with rearranged T cell receptors go once they leave the thymus?

Answer 44

they circulate in blood/lymphatics and some reside in the lymph nodes waiting for interactions with dendritic cells

Question 45

what happens if you fail positive and negative selection?

Answer 45

apoptosis

Question 46

where do immature dendritic cells take up and process antigens?

Answer 46

in the epidermis

Question 47

what happens once immature dendritic cells take up and process antigens?

Answer 47

they migrate to lymph nodes and mature en route

Question 48

what do mature dendritic cells have and do?

Answer 48

they have co-stimulatory activity and can prime naive T cells, they can also transfer antigen to dendritic cells resident in the lymph node

Question 49

what is required for activation and determining fate of T cells?

Answer 49

three signals

Question 50

what are the three signals needed to prime T cells?

Answer 50

1 - activation of T cells (MHC-TCR interactions) 2 - survival and clonal expansion of T cells, 3 - differentiation into subsets of effector T cells (specifically for CD4+ helper T cells)

Question 51

for CD8+ what does the third signal lead to?

Answer 51

effector function e.g. production of enzymes for degradation

Question 52

what enzymes induce target-cell apoptosis cooperatively?

Answer 52

perforin and granzyme

Question 53

what are the different subsets of the CD4+ T cell

Answer 53

TH1, TH2, TH17, TFH, Tregs

Question 54

what is TH1 found in

Answer 54

macrophage

Question 55

what is TH2 found in

Answer 55

allergic responses/plasma cell generation

Question 56

what is TH17 found in

Answer 56

epithelium and underlying tissue cell types

Question 57

where is TFH found?

Answer 57

in lymph nodes and is important for B cell antibody generation

Question 58

what do Tregs do?

Answer 58

control/dampen the immune response

Question 59

what is the main function of TH1 cells?

Answer 59

supporting macrophage function

Question 60

what is the main role of TH2 cells?

Answer 60

supporting humoral responses and allergic reactions

Question 61

what is TH2 the source of?

Answer 61

interleukin 4,5 and 6 which instruct B cells to produce antibodies

Question 62

what is TH1 the source of?

Answer 62

interferon-y

Question 63

what is the main role of TH17?

Answer 63

supporting innate immune responses and enhances clearance of extracellular bacteria and fungi

Question 64

what does TH17 produce?

Answer 64

interleukin-17 and 22

Question 65

what does IL17 stimulate?

Answer 65

epithelial cells to produce antimicrobial peptides

Question 66

what do Treg cells release?

Answer 66

inhibitory cytokines

Question 67

what do Treg cells inhibit?

Answer 67

T cell activation and dendritic cell activation

Question 68

how are CD8+ T cells activated?

Answer 68

from interactions between MHC I and TCR

Question 69

what do CD8+ T cells do?

Answer 69

induce host cells to undergo apoptosis and produce enzymes such as granzyme/perforin

Question 70

what does perforin do?

Answer 70

penetrate infected cells and target apoptotic signalling pathways

Question 71

what does T cell priming result in?

Answer 71

generation of memory T cells

Question 72

what is signal 3 of T cell priming?

Answer 72

cytokines drives differentiation of CD4+ T helper subsets

Question 73

what does granzyme do?

Answer 73

induce apoptosis