A4 T cells

Question 1

life of a t cell

Answer 1

-selected in thymus
-matures and migrates into periphery
-circulates through lymphnodes
-IF recognises antigen, activates acquires effector function

Question 2

T cell receptor (TCR) structure

Answer 2

2 protein chains paired together
-often α and β​
-sometimes γ and δ​
variable regions
-recognises diversity
transmembrane with cytoplasmic tail
-signalling upon recognition

Question 3

why is TCR selection required

Answer 3

generates huge diversity of antigen specific t cells
but not all will be useful
-self recognition
-dont recognise MHC
therefore selection is needed

Question 4

selection of t cells

Answer 4

selected in thymus
tcr is tested to confirm it works and doesnt recognise self
based on affinity, those with strong affinity are deleted

Question 5

2 types of useful T cells

Answer 5

CD4 helper t cells
CD8 killer t cells

Question 6

what does the t cell recognise

Answer 6

antigens
(short peptides from pathogen associated proteins that are generated after phagocytosis)

Question 7

how are antigens recognised

Answer 7

peptides presented to TCR in contect og major histocompatibilty complex (MHC)
two forms

Question 8

the two forms of MHC

Answer 8

MHC- CD8 T cells
MHCII- CD4 T cells

Question 9

what happens if T cell recognises antigen/MHC

Answer 9

-naive antigen specific t cells recirculate looking for phagocytes presenting their cognate antigen
-upon recognition t cell and antigen cell form interaction
-TCR transmits signals and T cell becomes activated

Question 10

what are the 4 T cell functions

Answer 10

proliferation
effector functions
memory
polarisation

Question 11

proliferation T cell function

Answer 11

huge diversity means antigen specific t cells are rare
activated t cells are useful so need to proliferate to generate effective immune response

Question 12

effector functions T cell function

Answer 12

CD4 T cells helper function
CD8 T cells killer function

Question 13

memory T cell function

Answer 13

key feature of adaptive immune system
vaccines
distinct from innate

Question 14

components of polarisation of CD4 T cell response

Answer 14

-Th1 secretes IFNg and activates macrophage functions
-Th2 secretes IL-4 and helps antibody production

Question 15

adaptive immunity advantages

Answer 15

random generation of specificity
-allows lymphocyte population to recognise antigenic peptides from many potential pathogens
-stops pathogens evading immune system

Question 16

adaptive immunity disadvantages

Answer 16

-not all antigens are harmful
-autoimmunity, allergy, food
-need cross talk between innate and adaptive to control this
-danger signal
(alarm signals from injured or stressed cells