L21- Clinical autoimmunity

Question 1

How can we classify autoimmune diseases?

Answer 1

The mechanism by which loss of tolerance has occurred
The presence and effects of autoantibodies
The extent to which different organs of the body are effected by the disease (tissue specific or systemic)

Question 2

What are the main mechanisms for loss of tolerance?

Answer 2

Ignorance - There are areas of the body that are invisible to the immune system such as the eyes and the testis due to potentially damaging immune responces that can occur. If a stabbing wound is inflicted then T cells can enter the eye and react to the previously hidden antigens.
Regulatory T cells-Failure of t regulatory cells results in autoimmunity as it prevents peripheral tolerance.
Inappropriate antigen presentation- Breakdown of regulatory mechanisms which prevent T cells helping production of self antibodies.

Question 3

What is goodpastures syndrome?

Answer 3

Autoimmune antibodies to basement membrane in kidneys and lungs

Question 4

What is rheumatoid arthritis?

Answer 4

Antibodies to the Fc portion of IgG

Question 5

What is myasthenia gravis?

Answer 5

Antibodies to the acetyl choline recpetor

Question 6

What are the 5 main mechanisms that antibodies produce autoimmune disease?

Answer 6

1. Complement dependent lysis of the target cell
2. Opsonisation
3. Formation of immune complexes
4. Blockage of receptors e.g. myesthenia gravis Ach receptor
5. Stimulation of cell surface receptors