Intro to autoimmunity

Question 1

Define autoimmunity

Answer 1

Break in self tolerance which results in the immune system mistakenly attacking self antigens.

Question 2

List 8 examples of autoimmune diseases

Answer 2

Systemic Lupus
Rheumatoid arhtriris
Multiple sclerosis
Vitiligo
Hashimoto's thyroiditis 
Type 1 diabetes
Grave's disease
Guillain Barre syndrome

Question 3

Describe the causes of AI diseases

Answer 3

Genetic factors (predispose you but does not directly cause it)
Infection and Environmental exposure (smoking, air pollution, drugs, stress, alcohol, tissue injury, infectious agents e.g virus, bacteria)

Question 4

What makes autoimmunity chronic and perpetuating

Answer 4

it is impossible to re-establish self-tolerance once it is broken

Question 5

Describe the mechanism of AI diseases

Answer 5

Susceptibility genes are present
Failure of self-tolerance
Persistence of self-reactive lymphocytes 
Environmental trigger
Activation of self-reactive lymphocytes 
Immune response against self antigens

Question 6

List the causes of immune regulatory failure and where they would occur

Answer 6

Loss of central tolerance (bone marrow and thymus)
Loss of peripheral tolerance (lymph nodes and spleen)
Molecular mimicry
Inappropriate activation

Question 7

WHAT IS molecular mimicry?

Answer 7

structural similarity on foreign pathogen that is a molecular mimic of self/host protein

Question 8

What is the target of the autoantibodies in:
Grave's disease
Myasthenia Gravis
Idiopathic Thrombocytopenic purpura
Guillain-Barre syndrome

Answer 8

TSH receptor
Acetyl choline receptor
Platelets
Gangliosides

Question 9

Revise the mechanism of Grave’s disease

Answer 9

Normally, TSH binds to the receptor on thyroid cells and stimulates release of thyroid hormones. If too much thyroid is produced there is a negative feedback loop which stops TSH release from he pituitary gland.

In Grave’s disease an autoantibody binds to the TSH receptor on the thyroid cell and stimulates excessive release of thyroid hormone. This occurs continuously and although the negative feedback loops works as normal, it does not prevent release of thyroid hormone as it is not TSH that is causing its release.

Question 10

Describe the mechanism of myasthenia gravis

Answer 10

Autoantibody binds to Acetyl choline receptor at the neuromuscular junction. Degradation of the receptors occurs so that there are fewer sites for neurotransmitters to bind. They also block the ACh receptors to prevent ACh from binding = no Na+ influx and no muscle contraction

Question 11

Describe the difference between organ specific and non-organ specific AI diseases

Answer 11

Organ specific: immune system attacks self antigens in on particular organ = damage of structure and function of organ

NOn-organ specific: immune system attacks widespread, systemic self antigens and is not restricted to one organ.