Autoimmunity

Question 1

The absence of specific immune response against some

antigens in an otherwise immunocompetent person ?

Answer 1

Tolerance

Question 2

A tolerance to self antigens (natural): ?

Answer 2

Autotolerance

Question 3

Induction of tolerance to an antigen at any
time during life. • Can be used for treatment of autoimmune
diseases, allergy & graft rejection. induced
?

Answer 3

Acquired tolerance

Question 4

Failure of autotolerance?

Answer 4

autoimmune disease.

Question 5

Mechanisms of Autotolerance (Self -Tolerance)

?

Answer 5

Central tolerance (Thymus & Bone marrow)  Peripheral tolerance (Peripheral tissues)

Question 6

Immature self-reactive lymphocytes are eliminated during their
maturation / Contact of immature B or T cells during development with antigen
?

Answer 6

Negative Selection

Question 7

Anergy?

Answer 7

1. Absence of costimulation
2. self-reactive T cells are unable to respond
3. Absence of T-cell help
   induces “
   anergy”

Question 8

Absence of costimulation → Anergy

self-reactive T cells are normally
rendered unable to respond ?

Answer 8

Peripheral T cell tolerance:

Question 9

Adaptive immune response to self-antigens

?

Answer 9

Autoimmunity

Question 10

production of autoantibodies and/or self reactive T
cells → autoimmune disease
?

Answer 10

Breakdown in autotolerance

Question 11

Etiology of autoimmune diseases

?

Answer 11

 “Breakdown of autotolerance”  “Multifactorial”

Question 12

Testicular trauma or infection → release of
sperm antigens → immune response → ab formation →
react with testicular tissue→ ↓ spermatogenesis
What type of Etiology of autoimmune diseases
?

Answer 12

Exposure to antigens that are normally
sequestered “hidden” within organs
“sequestered antigens”,

Question 13

Trauma → release of antigen → immune
response → destruction of lens

\type of Etiology of autoimmune diseases

Answer 13

Exposure to antigens that are normally
sequestered “hidden” within organs
“sequestered antigens”,

Question 14

Class II MHC are normally expressed ONLY on professional
antigen presenting cells (macrophages, dendritic cells and B cells).
 Under certain condition (may be viral infection)→ local
production of IFN-→ Increase class II MHC expression on a variety of cells → Abnormal expression of MHC II on tissue cells → recognition of these auto-antigens by self-reactive T cells

Type of Etiology of autoimmune diseases

Answer 14

Inappropriate class II MHC expression on non- antigen presenting cells

Question 15

Immune response directed originally against
these pathogens might cross react with host
tissues due to shared epitopes→ autoimmune
diseases.

Type of Etiology of autoimmune diseases
?

Answer 15

Etiology of autoimmune diseases

Cross-reactivity

Question 16

Streptococcus pyogenes and heart tissue antigens
M-protein of some strains of Streptococcus pyogenes
share epitopes with the heart muscle antigens .
Antibodies produced against M- protein of such
strains may cross react with heart tissue leading
to rheumatic fever and rheumatic heart disease

Type of Etiology of autoimmune diseases

Answer 16

Cross-reactivity “Molecular Mimicry”

Question 17

Certain microbes e.g., Epstein Barr virus (EBV) → non-specific activation of many clones of
lymphocytes (including self-reactive clones) → autoimmune response

Type of Etiology of autoimmune diseases
?

Answer 17

Polyclonal activation of lymphocytes

Question 18

Ab against thyroid cells → mimic the effect of TSH (thyroid stimulating hormone) → ↑ secretion of thyroxin → Thyrotoxicosis
Is?

Answer 18

Grave’s disease