B4 on and off good vs bad

Question 1

what if tolerance fails

Answer 1

if T cell escapes clonal deletion in thymus and isnt tolerised in periphery, can become activated
-to non harmful antigens=allergy
-to self antigens=autoimmunity

Question 2

organ specific autoimmune diseases

Answer 2

-T1D
-goodpastures symdrome
-MS
-chrons
-psoriasis
-graves disease
-hashimotos thyroiditis
-autoimmune hemolytic anemia
-addisons disease
-vitiligo
-myasthenia gravis

Question 3

systemic autoimmune disease

Answer 3

-rheumatoid arthritis
-scleroderma
-systemic lupis
-polymyostitis

Question 4

central tolerance

Answer 4

selects cell based on affinity
approx 95% cells deleted
-failing +ve and -ve selection

Question 5

peripheral tolerance

Answer 5

prevents immune responses to other antigens
-eg food antigens, goog bacteria, autoantigen

Question 6

what happens if immune response (tolerance) fails

Answer 6

immunodeficiencies
immune evasion by pathogens

Question 7

2 types of immunodeficiencies

Answer 7

primary
-genetically acquired
secondary
-infections
-metabolic dysregulation
-therapeutically-induced

Question 8

what is central tolerance (adaptive immune system)

Answer 8

generates diverse range of antigen specific cells, all recognising different antigens
high potential that cells will recognise self antigens

Question 9

CT
education where removes self reactive cells by what method

Answer 9

thymus
clonal deletion

Question 10

what is thymic selection dependent on

Answer 10

affinity of TCR for MHC

Question 11

positive selection in CT

Answer 11

-T cells that dont have enough affinity dont receive survive signal
-selects for T cells with TCR of moderate /high for MHC
-ensure mature t cells can recognise MHC and antigen in periphery

Question 12

negative selection in CT

Answer 12

-removes T cells that bind too strongly
-ensures self reactive T cells are clonally deleted

Question 13

why are potentially harmful self reactive (or autoreactive) T cells removed

Answer 13

they have high affinity for self antigens presented by MHC

Question 14

why is a mechanism of peripheral tolerance required

Answer 14

not all antigens presented in thymus (sex hormones)
not all antigens we should tolerate are present during thymic selection (food antigens)

Question 15

what cytokines inhibit other self reactive T cells

Answer 15

IL-10 and TGF-B produced by Treg cells