Autoimmunity

Question 1

What is autoimmunity?

Answer 1

the breakdown in the integrity of immune tolerance such
that humoral and cellular immune responses can be mounted against host tissues or
antigens, leading to localize or systemic injury.

Question 2

Autoantibodies

Answer 2

When antibodies react with individual’s tissues causing inflammatory reaction and tissue damage

Question 3

3 causes of autoimmunity

Answer 3

1. Neoantigens
2. Molecular mimicry
3. Failure of tolerance

Question 4

How do neoantigens cause autoimmunity?

Answer 4

Neoantigens are haptens, when they bind to a host protein it becomes immunogenic, resulting in an immune response against the altered host protein

Question 5

Molecular mimicry

Answer 5

A foreign antigen very closely resembles a self antigen. Antibodies produced foreign antigen also react with self antigens = cross reactive antibodies

Question 6

How does group a beta-hemolytic strep cause rheumatic fever?

Answer 6

myocardial heart valve cells are similar to group A beta-hemolytic streptocci
=
Antibodies and memory cell’s trigger reaction resulting in myocarditis

Question 7

Immunologic tolerance

Answer 7

Ability of immune system to differentiate self from non self
MHC molecule is a recognition marker

Question 8

Central tolerance

Answer 8

Elimination of self reactive (auto reactive) T and B cells in the central lymphoid organs (thymus and bone marrow)`

Question 9

3 Actions during central tolerance of T cells

Answer 9

In the thymus:
1. If T cells does not react to self = death
2. Clonal deletion: If T cell binds strongly to self, it is destroyed (negative selection)
3. If T cell binds weekly to self, it is allowed to leave the thymus (positive selection)

Question 10

Positive selection

Answer 10

Lymphocytes that react weekly with self, get to live and develop

Question 11

Negative selection

Answer 11

Lymphocytes that react strongly to self = DEATH

Question 12

Define peripheral tolerance of T cells

Answer 12

Is the deletion or inactivation of autoreactive T cells that escaped death in
the thymus during the process of central tolerance

Question 13

Steps to peripheral tolerance of T cell

Answer 13

1. CD4 and CD8 molecules help APC and T cell bind (help activate T cell)
2. Binding of T cell and APC results in the T cell being primed and idling
3. To kick the T cell out of idling, it has to receive a co-stimulatory signal from IL 1 and other cytokines
4. If a T cell is auto reactive, other cytokines are not released and the cell stays in a state of anergy if THIS FAILS = autoimmunity

Question 14

3 actions during central tolerance of B cells

Answer 14

1. B cells that make no receptors = DEATH
2. B cells receptors that bind too strongly to self
   a) Self cell sends signal to B cells to change antibodies, if it does we KEEP
   b) If it doesn’t= DEATH
3. Receptors do not bind too strongly to self = KEEP