adaptive immunity: T-cells

Question 1

what do T cells do?

Answer 1

drive cell-mediated immunity, involving activation of macrophages, NKC’s and antigen-specific cytotoxic T-lymphocytes

Question 2

what do B cells do?

Answer 2

produce antibodies and drive humoral immunity

Question 3

what is immunological memory?

Answer 3

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

Question 4

when does the adaptive immune response occur?

Answer 4

following the innate immune response, 4-7 days after infection

Question 5

what are the main receptors in adaptive immunity?

Answer 5

T cell receptor, B cell receptor, MHC proteins

Question 6

Where are T cells derived and where do they mature?

Answer 6

bone marrow, thymus

Question 7

what do t cells give rise to?

Answer 7

cellular immunity

Question 8

how do t cells recognize peptides?

Answer 8

through T Cell Receptor

Question 9

What is thymic education?

Answer 9

T cells only respond to foreign pathogens and not self-peptides

Question 10

what are T helper cells?

Answer 10

function to help support other immune cells to fight threats

Question 11

what are cytotoxic t cells?

Answer 11

destroy own cells which have become infected

Question 12

what are Tregs ?

Answer 12

regulate or suppress other cells in immune system

Question 13

what do t cells start out as?

Answer 13

naïve cells and have receptor for very specific proteins

Question 14

what are CD8 receptors?

Answer 14

co-receptor that binds to MHC1

Question 15

what are CD4 receptors?

Answer 15

co-receptor that binds to MHC2

Question 16

what are CD3 receptors?

Answer 16

co-receptor involved in activation of CD8 & CD4

Question 17

what chains are t cell receptors usually made of?

Answer 17

alpha and beta

Question 18

what chains are a small proportion of t cells made of?

Answer 18

gamma and delta

Question 19

describe the constant region

Answer 19

doesn’t change

Question 20

describe the variable region

Answer 20

helps receptor bind to antigen- structural changes

Question 21

which gene segment encodes both alpha and beta chains?

Answer 21

variable

Question 22

what does diversity gene segment encode?

Answer 22

beta chain only

Question 23

what does joining gene segment encode?

Answer 23

both alpha and beta chains

Question 24

what is somatic recombination?

Answer 24

how genes are re-arranged, driven by RAG (recombinase) enzymes, recombination leads to a different receptor

Question 25

what cells do t cells interact with in thymus?

Answer 25

cortical epithelial cells

Question 26

what is positive selection?

Answer 26

no recognition=apoptosis

Question 27

what is negative selection?

Answer 27

recognition of self antigen=apoptosis

Question 28

what is t cell emigration?

Answer 28

+ and - selected CD8 & CD4 t cells with rearranged receptors leave thymus and circulate in blood/lymphatics, some reside in lymph nodes, still classed as naïve

Question 29

how are t cells activated by dendritic cells?

Answer 29

immature dendritic cells take up and process antigen in the epidermis, then migrate to lymph notes and mature en route, mature dendritic cells have co-stimulatory activity and can prime naïve t cells

Question 30

why does priming require 3 signals?

Answer 30

for activation and determining the fate of t cells

Question 31

what does signal 1 do?

Answer 31

activation of t cells

Question 32

what does signal 2 do?

Answer 32

survival and clonal expansion of t cells

Question 33

what does signal 3 do?

Answer 33

differentiation into subsets of effector t cells

Question 34

what does the 3rd signal do in CD8's?

Answer 34

leads to effector function

Question 35

what is signal 1 but no 2?

Answer 35

anergy

Question 36

what are the CD4 subsets?

Answer 36

Th1, Th2, Th17, Tfh, Treg,

Question 37

what do Th1 cells do?

Answer 37

support cellular immunity support macrophage function source of interferon-gamma

Question 38

what does Th2 do?

Answer 38

support humoral responses and allergic reactions, source of interleukin-4,5 and 6 which instruct B cells to produce antibodies

Question 39

what do Th17 cells do?

Answer 39

support innate immune response | enhance clearance of extracellular bacteria and fungi, IL-17, IL-22

Question 40

what do Tfh cells do?

Answer 40

found in secondary lymphoid organs in B cell zone, work with B cells for antibody production

Question 41

what do Treg cells do?

Answer 41

``` function in immune suppression release inhibitory cytokines, inhibit t cell activation and dendritic cell activation ```

Question 42

what do CD8 cells do?

Answer 42

activated from interactions between MHCI and TCR induce host cells to undergo apoptosis produce enzyme such as granzyme, perforin-targets apoptotic signalling pathways