autoimmunity

Question 1

immunological tolerance

Answer 1

unresponsiveness to antigen that is induced by previous exposure to that antigen
sam antigen may induce immune response or tolerance depending on conditions of exposure

Question 2

self-tolerance

Answer 2

tolerance to self-antigens

failure results in immune reactions against self - autoimmunity

Question 3

tolerogens

Answer 3

antigens that induce tolerance

Question 4

central tolerance

Answer 4

thymus eliminates T cells with high affinity to self-antigens

bone marrow and B cells

Question 5

peripheral tolerance

Answer 5

mature lymphocytes recognise self-antigens in peripheral tissues become inactivated or die by apoptosis

Question 6

mechanisms of peripheral tolerance

Answer 6

anergy - functional unresponsiveness
antigen recognition without co-stimulation
Treg suppression
deletion - cell death
sequestered from immune system by anatomic barriers

Question 7

peripheral tolerance can result from

Answer 7

inapprop access to self antigens
inapprop/increased local expansion of co-stimulatory molecules
alterations in the way self-molecules are presented to immune system

Question 8

autoimmunity

Answer 8

adaptive immune response to self-antigens

autoimmune diseases occur when autoreactive T cells/autoantibodies cause tissue damage through hypersensitivity II, III, IV

Question 9

autoantibodies

Answer 9

antibodies directed at normal cellular components (autoantigen)

Question 10

what are natural antibodies

Answer 10

B1 cells secrete natural antibodies

major source of autoantigens

Question 11

what do natural antibodies do

Answer 11

• bind to antigens on variety of bacteria, activate complement and clear bacteria
• cross react with inherited A or B antigens, individuals make IgM anti-A/B antibodies
• can bind to normal cellular constitutes

Question 12

breakdown of T cell tolerance: genetic factors

Answer 12

clusters within families
alleles of MHC e.g. HLA-B27
AIRE gene mutated - central tolerance can't happen 
common polymorphisms 
rare genetic diseases

Question 13

breakdown of T cell tolerance: environmental factors

Answer 13

infections: molecular mimicry, up regulation of co-stimulation
drugs: molecular mimicry, genetic variations of drug metabolism
UV radiation: trigger for skin inflammation, modification of self-antigen

Question 14

molecular mimicry

Answer 14

structural similarities between self-proteins and microbial antigens may trigger autoimmune response

Question 15

risk factors for autoimmune disease

Answer 15

genetics:

• AIRE gene mutation
• polymorphisms in insulin gene
• MHC polymorphism

environment

• infection
• medications
• UV light

Question 16

non-organ specific autoimmune disease

Answer 16

multiple organs
assoc w autoimmune response against self-antigens widely distributed throughout body
intracellular molecules involved in transcription + translation

Question 17

organ-specific autoimmune disease

Answer 17

restricted to one organ

Question 18

MXx autoimmune disease: suppression of damaging immune response

Answer 18

before irreversible tissue damage

early detection is a challenge

Question 19

Mx autoimmune diseases

Answer 19

replacement of function of damaged organ e.g. insulin dependent DM

anti-inflammatory drugs - corticosteroids
immunosuppression