Tolerance, Autoimmunity, and Transplantation

Question 1

Tolerance:

Answer 1

The immune system’s ability to recognize and ignore self-antigens to prevent autoimmune diseases.

Question 2

Self-tolerance:

Answer 2

The process by which immune cells are educated to not react against the body’s own tissues.

Question 3

Central tolerance:

Answer 3

Occurs in primary lymphoid organs (thymus for T cells, bone marrow for B cells) where cells that strongly react with self-antigens are eliminated.

Question 4

Peripheral tolerance:

Answer 4

Occurs outside primary lymphoid organs and involves mechanisms like regulatory T cells (Tregs) that suppress autoreactive immune cells.

Question 5

Autoimmunity:

Answer 5

A condition where the immune system mistakenly attacks the body’s own tissues due to a breakdown in self-tolerance.

Question 6

Examples of autoimmune diseases:

Answer 6

Type 1 diabetes, rheumatoid arthritis, multiple sclerosis, lupus, and Hashimoto’s thyroiditis.

Question 7

Molecular mimicry:

Answer 7

When foreign antigens resemble self-antigens, triggering an autoimmune response (e.g., rheumatic fever after a streptococcal infection).

Question 8

Regulatory T cells (Tregs):

Answer 8

T cells that help maintain tolerance by suppressing other immune cells that could potentially attack self-tissues.

Question 9

Autoantibodies:

Answer 9

Antibodies produced by the immune system that mistakenly target and damage the body’s own tissues.

Question 10

Th17 cells in autoimmunity:

Answer 10

A subset of helper T cells that can contribute to autoimmune inflammation, particularly in conditions like multiple sclerosis.

Question 11

Immunological tolerance and vaccines:

Answer 11

Vaccines must avoid breaking tolerance to self-antigens while stimulating immunity to pathogens.

Question 12

Transplantation tolerance:

Answer 12

The ability of the immune system to accept a transplanted organ without rejection.

Question 13

Alloreactivity:

Answer 13

The immune response to transplanted tissue, where the recipient’s immune system targets the donor’s MHC molecules as foreign.

Question 14

Graft rejection:

Answer 14

The immune system’s response against a transplanted organ or tissue, mediated by T cells and antibodies.

Question 15

Hyperacute rejection:

Answer 15

A rapid immune response against a transplanted organ that occurs within minutes to hours, usually due to pre-existing antibodies.

Question 16

Acute rejection:

Answer 16

A more gradual immune response (days to months) where T cells attack the transplanted organ or tissue.

Question 17

Chronic rejection:

Answer 17

A long-term immune response that slowly damages the transplanted tissue over time, often leading to organ failure.

Question 18

Immunosuppressive drugs:

Answer 18

Medications that suppress the immune system to prevent graft rejection, often used after organ transplantation.

Question 19

HLA mismatch:

Answer 19

The differences in human leukocyte antigens (HLA) between donor and recipient that contribute to graft rejection.

Question 20

Bone marrow transplantation:

Answer 20

A procedure to replace damaged or diseased bone marrow with healthy marrow, often used to treat leukemia or other blood disorders.

Question 21

Graft-versus-host disease (GVHD):

Answer 21

A complication of bone marrow transplantation where the donated immune cells attack the recipient’s tissues.

Question 22

Induction immunosuppression:

Answer 22

Intense immunosuppression used immediately after transplantation to prevent rejection, typically with monoclonal antibodies or high-dose steroids.

Question 23

Maintenance immunosuppression:

Answer 23

Ongoing immunosuppressive therapy to prevent chronic rejection after organ transplantation.

Question 24

Tolerance induction in transplantation:

Answer 24

Strategies to promote long-term acceptance of a transplant without the need for lifelong immunosuppressive therapy.

Question 25

T cell tolerance in transplantation:

Answer 25

T cells that recognize donor antigens must become tolerant to prevent graft rejection.

Question 26

Donor-specific transfusion (DST):

Answer 26

A technique used to induce immune tolerance in transplant recipients by exposing them to donor cells before transplantation.

Question 27

Crossmatch test:

Answer 27

A test performed before organ transplantation to ensure that the recipient’s immune system will not attack the donor organ.

Question 28

Molecular tolerance in transplantation:

Answer 28

The idea of inducing tolerance to the transplant at the molecular level by modulating immune responses, such as through regulatory T cells.

Question 29

Tolerance and autoimmune diseases:

Answer 29

Breakdown of immune tolerance leads to autoimmune diseases, where self-reactive immune cells attack the body’s own tissues.

Question 30

Immune checkpoint inhibitors and autoimmunity:

Answer 30

Checkpoint inhibitors used in cancer therapy can enhance immune responses, but may lead to autoimmune reactions in some cases.

Question 31

Hematopoietic stem cell transplantation (HSCT):

Answer 31

The transplantation of hematopoietic stem cells to restore the blood and immune systems, often used for blood cancers.