A4 T cells Flashcards

t cell recognition

1
Q

life of a t cell

A

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

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2
Q

T cell receptor (TCR) structure

A

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

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3
Q

why is TCR selection required

A

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

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4
Q

selection of t cells

A

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

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5
Q

2 types of useful T cells

A

CD4 helper t cells
CD8 killer t cells

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6
Q

what does the t cell recognise

A

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

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7
Q

how are antigens recognised

A

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

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8
Q

the two forms of MHC

A

MHC- CD8 T cells
MHCII- CD4 T cells

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9
Q

what happens if T cell recognises antigen/MHC

A

-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

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10
Q

what are the 4 T cell functions

A

proliferation
effector functions
memory
polarisation

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11
Q

proliferation T cell function

A

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

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12
Q

effector functions T cell function

A

CD4 T cells helper function
CD8 T cells killer function

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13
Q

memory T cell function

A

key feature of adaptive immune system
vaccines
distinct from innate

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14
Q

components of polarisation of CD4 T cell response

A

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

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15
Q

adaptive immunity advantages

A

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

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16
Q

adaptive immunity disadvantages

A

-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