Tolerance and Autoimmunity Flashcards
What is tolerance?
prevention of an immune response against self-structures
Describe central tolerance.
deletion of lymphocytes before they mature
- in bone marrow and thymus
Describe peripheral tolerance.
generates inhibiting lymphocytes such as Treg or apoptosis of self reactive cells
- occurs in secondary lymphoid tissues
How does the immune system maintain tolerance?
- Antigen evasion: protects tissue-specific antigens from exposure
- Eye, CNS, testes - Central tolerance: deletes autoreactive T and B cells
- Peripheral tolerance: regulates autoreactive cells in circulation
- Treg = CTLA-4
- IL-10, TGF-b
What causes autoimmunity?
Failure of tolerance processes
List the 5 autoimmune disorders.
- Diabetes Mellitus
- Myasthenia Gravis
- Lupus
- Multiple Sclerosis
- Rheumatoid Arthritis
What is Type 1 Diabetes target, the mechanism, and response?
Target: attack insulin-producing beta cells in pancreas
Mechanism: CTLs infiltrate pancreas and activate macrophages or ADCC
Response: DTH
What is Myasthenia Gravis target, the mechanism, and response?
Target: autoantibodies bind acetylcholine receptors
Mechanism: block normal binding of ACh on motor end plate and induces complement-mediated lysis
Response: weakened skeletal muscles
What is Lupus target, the mechanism, and response?
Target: autoantibody against DNA
Mechanism: antibody/antigen complexes get stuck
Response: fever, kidney damage, rashes, weakness
- Type III
- common in women
What is Multiple Sclerosis target, the mechanism, and response?
Target: myelin sheath
Mechanism: autoreactive T cells form inflammatory lesions along myelin sheath around nerve fibers
Response: numbness, paralysis
What is Rheumatoid Arthritis target, mechanism, and response?
Target: IgG
Mechanism: Auto-antibody reactive with Fc region of IgG
Response: activate complement cascades
- chronic joint inflammation
- between 40 to 60 years old
