Self-tolerance is maintained through central and peripheral mechanisms in the immune system. In the central mechanism, immature T and B cells that recognize self-antigens in the thymus and bone marrow undergo apoptosis or receptor editing. In the peripheral mechanism, lymphocytes encountering self-antigens are anergized, suppressed by regulatory T cells, or deleted through apoptosis to prevent autoimmune responses.

1. 10 – 15 min 15 Slides Jan 14, 2019
Self
Objective

2. What’s Asthma?What’s the coronary circulation?
Objective
Define self-tolerance and explain its mechanisms

3. Self Tolerance
Self-tolerance refers to lack of immune
responsiveness to one's own tissue antigens.

4. Betaβ cellsMechanism
Central Peripheral

5. Betaβ cellsCentral
Pe
Antigen-induced Deletion of self-reactive
T lymphocytes & B lymphocytes during their
maturation in central lymphoid organs
ntigens
c APCs.
such a
s

6. Betaβ cellsCentral
Pe
in Thymus, many autologous protein antigens
are processed and presented by thymic APCs.
Any immature T cell that encounters such a
self antigen undergoes apoptosis
elf
Some
nto

7. Betaβ cellsCentral
Pe
Not all immature T cells that see self
antigens in the thymus are deleted. Some
CD4+ T cells survive and develop into
regulatory T cells
cells to
ergo

8. Betaβ cellsCentral
Pe
in Bone Marrow, reactive Immature B cells to
self antigens with high affinity undergo
Apoptosis or Receptor Editing.
sent in
nce
such
hery.

9. Betaβ cellsCentral
Pe
However, Not all self antigens are present in
the Thymus or Bone Marrow, & hence
lymphocytes bearing receptors for such
autoantigens escape into the periphery.

10. Betaβ cellsPeripheral
Anergy
Suppression
Deletion
functio
of lymp
with

11. Betaβ cellsAnergy
functional inactivation rather than Apoptosis
of lymphocytes that is induced by encounter
with antigens under certain conditions
Suppression
Deletion

12. Betaβ cellsSuppression
By Treg cells, their inhibitory activity mediated
by immunosuppressive cytokines which inhibit
lymphocyte activation & effector functions.
Deletion
Deletion

13. Betaβ cells
T cells that recognize self antigens may receive
signals that promote their death by apoptosis.
Deletion
Deletion

14. Summary

15. Sources? N S H
Advisor >
• Dr. Abdulaziz.
Websites >Robbins 9th > QuMed >
• Autoimmunity.