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Flashcards in T-cell development Deck (20)
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1

Humoral immunity definition

B-cell response resulting in antibody production

2

Cell-mediated immunity definition

T-cell response

3

T-cell maturation

T-cells are educated in the thymus to prevent autoimmunity

They must undergo positive and negative selection before they are released into the blood

4

T-cell positive selection

Must bind MHC-peptide complexes

Facilitated by cortical thymic epithelial cells (cTECs)

5

T-cell negative selection

Must ignore self antigens

Facilitated by medullary thymic epithelial cells

6

Naive T-cells

Have not encountered antigen since leaving the thymus

7

Effector T-lymphocytes

Have acquired effector functions and are able to enter peripheral tissues after antigen binding

8

Memory cells

Remain in a resting state after the pathogen has been destroyed

9

Immunological synapse

When naive T-cells encounter complementary antigen, they stop migrating and bind, forming an immunological synapse

This synapse is stabilised by adhesion molecules such as ICAM-1

10

T-cell antigen recognition

The TCR requires co-stimulation for full activation

-CD80/CD86
These bind to CD28 on the TCR

Expression of co-stimulatory molecules is induced by microbial products

Lack of co-stimulation results in anergy

11

T-cell signal transduction

When binding to the TCR has occured, the signal is transmitted intracellularly

This occurs when kinase Lck phosphorylates and activates ITAMs

12

T-cell clonal expansion

Proliferation of T-cells is induced by cytokines

This is mainly IL-2, which acts via an autocrine mechanism

13

T-cell differentiation

During an immune response, further cytokine signals induce T-cells to differentiate into different types of effector cells

14

Th1 cells

Stimulated by: IL-12, IL-16 & IFNy

Respond to intracellular pathogens & are pro-inflammatory

Effector cytokines = IL-2, TNFa, IFNy

15

Th2 cells

Stimulated by: IL-4

Cause mast cell, eosinophil and B-cell activation, respond to helminthic parasites

Stimulate IgE production

Effector cytokines = IL-4, IL-5, IL-13

16

Treg cells

Stimulated by = IL-2, TGFB

Cause peripheral tolerance & are anti-inflammatory

Effector cytokines = TGFB, IL-10

17

Th17 cells

Stimulated by = IL-1, IL-6, TGFB

Respond to bacterial infections & are pro-inflammatory

Effector cytokines = IL-17, IL-22

18

TfH cells

Stimulated by = IL-6, IL-21

Cause B-cell activation, antigen switching & affinity maturation

Effector cytokines = IL-4, IL-21

19

Th1 / Th2 balance

Th1 and Th2 inhibit the production of each other in a process called cross-regulation

This process involves transcription factors T-Bet and GATA-3

20

CD8 T-cell co-stimulation

CD8 T-cells require further co-stimulation

-IL-2 (produced by CD4 T-helper cells)
-CD40/CD40L