![Definition:
Tolerance is specific immunologic
unresponsiveness
i.e., an immune response to a certain antigen
[or epitope] does not occur, although the
immune system is otherwise functioning
normally](https://image.slidesharecdn.com/toleranceandautoimmunity-190503044114/85/Tolerance-and-autoimmunity-5-320.jpg)
Tolerance and autoimmunity
- 1. Dr Muhammad Omair Riaz MBBS, FCPS (Immunology) Consultant Immunologist
- 3. Should be able to: Define tolerance Enumerate types of tolerance Give an overview of their mechanisms List important autoimmune diseases List important drugs in treatment of autoimmunity
- 4. Review of Medical Microbiology & Immunology http://immense-immunology- insight.blogspot.com
- 5. Definition: Tolerance is specific immunologic unresponsiveness i.e., an immune response to a certain antigen [or epitope] does not occur, although the immune system is otherwise functioning normally
- 6. “Deletion of self-reactive T-cell precursors in the thymus” In general, antigens that are present during embryonic life are considered “self ” and do not stimulate an immunologic response (i.e., we are tolerant to those antigens)
- 7. T CellTolerance B CellTolerance
- 8. Types: Central tolerance: Thymus Mechanism: ▪ Clonal deletion Peripheral tolerance: Outside thymus Mechanism ▪ Clonal anergy
- 12. Peripheral tolerance is necessary because some antigens are not expressed in the thymus and therefore some self reactive T cells are not killed in the thymus. There are several mechanisms involved in peripheral tolerance
- 14. NormalT Cell Activation In case of clonal anergy
- 15. Types: Central tolerance: Bone marrow Mechanism: ▪ Clonal deletion and receptor editing Peripheral tolerance: Outside bone marrow Mechanism ▪ Clonal anergy
- 16. To avoid clonal deletion , B cells undergo receptor editing Upto 50% of all B cells undergo receptor editing
- 17. Age Lower age enhances tolerance Structure & dose of antigens Lower doses induce tolerance Administration of immunosuppressive drugs Induces tolerance Type of cells involved T cells become tolerant more readily Administration of a cross-reacting antigen Terminates tolerance.
- 20. Definition Loss of tolerance to self antigens
- 21. The most important step in the production of autoimmune disease is the activation of self- reactive helper (CD4)T cells. These self-reactive cells can induce either cell-mediated or antibody-mediated autoimmune reactions, respectively
- 22. These can be: Genetic Endogenous/ Hormonal Environmental
- 24. 1. Molecular mimicry Immune response against a substance can induce immune response against it’s molecular analogues 2. Alteration of Normal Proteins 3. Release of SequesteredAntigens Due to disease etc 4. Epitope Spreading 5. Failure of regulatoryT cells
- 25. SLE RA PemphigusVulgaris IDDM Grave’s disease Coeliac disease
- 28. Time for The mandatory Quiz!!!
- 29. Immunologic tolerance is an example of 1. Incomplete immune response 2. Ineffective immune response 3. Partial immune response 4. Absent immune response 5. No immune response
- 30. What induces tolerance? 1. Deletion of self reactiveT cells in thymus 2. Deletion of self reactiveT cells in Bone marrow 3. Deletion of self reactive B cells in thymus 4. Deletion of self reactive B cells in Bone marrow
- 31. Negative selection ofT cells in thymus is an example of: 1. Clonal anergy 2. Clonal deletion 3. Receptor editing 4. Breakdown of tolerance 5. None of the above
- 32. All of these are mechanisms of peripheralT cell tolerance except 1. Clonal anergy 2. Clonal deletion 3. Inhibition by regulatoryT cells 4. Positive selection of self reactiveT cells 5. None of the above
- 33. All of these are mechanisms of autoimmunity except: 1. Molecular mimicry 2. Release of Sequestered Antigens 3. Epitope Spreading 4. Failure of regulatoryT cells 5. Negative selection of self reactiveT cells
- 34. Following factors are a cause of autoimmune disease, except: Genetic factors Hormonal factors Environmental factors Dietary factors None of the above You got it wrong coz you were busy whatsapping!
- 35. Download the presentation from www.slideshare.net/omairriaz