Immune Tolerance Flashcards

Question

How are T cells centrally tolerated?

Answer 1

T cell selection occurs in the thymus Need to select for T cell receptor that’s capable of binding self MHC T cell receptor don’t bind to any self-MHC —> death by apoptosis T cell binds too strongly to self-MHC —> apoptosis triggered - negative selection T cell bins=do weakly to self-MHC —> signal to survive - positive selection

Answer 2

Autoimmune regulator A specialised transcription factor that allows thymidine expression of genes tat are expressed in peripheral tissues —> promotes elf tolerance by allowing the tunic expression of genes from other tissues

Answer 3

Destroy or control any self reactive T or B cells which enter the circulation

Answer 4

Antibody production Memory Affinity maturation —> recognise antigen and change shape of antibody to better bind to it

Answer 5

Normally good but exposure to environmental antigens or self antigens in context of infections can alter the outcome

Answer 6

Naive T cells need co-stimulatory signals in order to become activated Most cells lack co-stimulatory proteins and MHC class II If naive T cells sees firs MHC w/out appropriate costimulatory protein —> becomes anergic —> deactivated Less likely to be stimulated in future

Answer 7

Antigen may be present in too low a conc. to reach the threshold for T cell receptor triggering Happens in immunologically privileged sites —> T cells never sees antigen so can ‘ignore’ it Also happens in compartmentalisation of cells and antigens —> T cell never encounters antigen so never becomes reactive

Answer 8

Activated through the T cell receptor can result in apoptosis Influenced by the nature if the initial T cell activation events In peripheral T cells —> often caused by induction of expression of the death ligand —> Fas ligand

Answer 9

Sunset of helper T cells that inhibit other T cells and other cells

Answer 10

CD4 High IL-2 receptor (CD25) Foxp3 transcription factors

Answer 11

Secretion of immune-suppressive cytokines Inactivation of dendritic cells or responding lymphocytes

Answer 12

Severe and fatal autoimmune disorder -immune dysregulaton, Polyendocrinopathy, Enteropathy X linked (IPEX) syndrome

Answer 13

Key anti-inflammatory cytokine Multi-functional —> acts on a range of cells Block pro-inflammatory cytokine synthesis Downregulates macrophage functions Viral mimics

Answer 14

Critical when mother is exposed to antigens often expressed in context of MHC I in baby —> half of baby’s from dad so foreign

Answer 15

Development in thymus requires recognition of self antigen during T cell maturation Residues in peripheral tissues to prevent armful rations against self

Answer 16

Develop from mature CD4 T cells that are exposed to antigen in periphery —> no role for thymus May be generated in all immune responses to limit collateral damage

Answer 17

They program immune response —> focus it for the right kind of response Can be inflammatory or anti-inflammatory

Answer 18

Drive movement around the body Act like address labels sending stuff to the right place Receptor profile change with activation state of the cells

Answer 19

T helper type is defined by transcription factors —> Cytokines shape transcription factor pathways Cross regulation is where cytokine response from 1 type of Th cell will shutdown the response of other Th cell types

Answer 20

Different antibody classes have different constant regions which is important for their functions Difference in function reflect the different types of response required to clear pathogens There are a number of gene cassettes that can be swapped in and out T cell produce cytokines which programme B cells to activate gene factors to switch Ig classes