Immunological Tolerance And Autoimmunity

Question 1

Differentiate acquired tolerance from immunity, immunodeficiency, and immunosuppression

Answer 1

Tolerance: specific immunological unresponsiveness triggered by previous exposure to specific antigen.
Immunity:
Immunodeficiency: Condition in which there is a deficiency or inability to mount a humoral and/or cell-mediated immune response (LACKS specificity to antigen)
Immunosuppression: Suppression of immune responses to antigens due to physical or chemical insults (LACKS specifics to antigen)

Question 2

Describe the elements of antigen dose, form, and route of administration that favor the formation of acquired immune tolerance

Answer 2

Dose: very large or very small
Form: soluble, aggregate-free, simple small molecules, not processed
Route: oral or sometimes intravenous

Question 3

Describe the mechanisms associated with central tolerance and peripheral tolerance

Answer 3

Central: Occurs in central lymphoid organs as a consequence of immature self-reactive lymphocytes recognizing ubiquitous self-antigen
- Thymus for T-Cells
- Bone Marrow for B-Cells
Peripheral: Induced in peripheral organs as a result of mature self-reactive lymphocytes encountering tissue-specific self antigens under particular conditions

Question 4

Explain how autoantibodies can cause hyperactivity or hypoactivity in a target organ (Use Hashimoto’s Thyroiditis and Grave’s Disease as prototypical autoimmune diseases)

Answer 4

Hyperactivity – Such as hyperthyroidism seen in Grave’s Disease – antibody binds to thyroid-stimulating hormone receptor and ACTIVATES (agonist)

Hypoactivity – Such as hypothyroidism seen in Hashimoto’s Thyroiditis – thyroid-specific antibodies destroy the thyroid tissue and it becomes infiltrated with leukocytes

Question 5

Recognize the importance of immunologically privileged sites.
Identify the 5 human immunologically privileged sites

Answer 5

Damage to immunologically privileged sites can lead to autoimmunity.

1. Brain
2. Eye
3. Testis
4. Ovary
5. Uterus