CSIM 1.58 - Autoimmunity 2

Question 1

Define type 2 hypersensitivity reactions?

Answer 1

Reactant (allergen) binds to cells within the body and forms a cell/matrix associated Ag. The body produces IgG (ANTIBODY) to counter the complex

Question 2

What is exopthalmos?

Answer 2

Bulging eyes

Question 3

Where is TSH secreted from and where does it act?

Answer 3

Pituitary gland

Acts on thymus

Question 4

Describe how XS thyroid hormones may be produced as a result of autoimmunity?

Answer 4

Autoimmune antibodies secreted from B-cells target the TSH-receptors and stimulate thyroid hormone secretion from the thyroid. Negative feedback acts on the pituitary to stop releasing TSH - the auto-antibodies continue to stimulate

Question 5

What is it and which specific hormones are elevated and suppressed in Grave’s disease?

Answer 5

Hyperthyroidism
Increased thyroxine (T4) and Triiodothyronine (T3)
Supressed TSH

Question 6

What are the six symptoms of Grave’s disease?

Answer 6

Tachycardia
Tremor
Weight loss
Diarrhoea
Exopthalmos
Goitre

Question 7

What is thyroiditis and what can it lead to?

Answer 7

Inflammation of the thyroid gland associated with thyroid peroxidase antibodies leading to hypothyroidism

Question 8

What are the symptoms of hypothyroidism?

Answer 8

Bradycardia
Rigidity
Weight gain
Constipation

Question 9

Name three common autoimmune endocrine diseases?

Answer 9

Type 1 diabetes - destruction of Beta islets of Langerhan
Pernicious anaemia - Vit-B12 deficiency
Addison’s disease - hypoadrenalism - decreased cortisol

Question 10

Describe haemolytic anaemia and which antibody in particular is bad?

Answer 10

Auto-antibody against RBC membrane Ag destroys RBC

IgM agglutinates red cells and activates complement (MAC rapidly destroys RBC)

Question 11

Describe myesthenia gravis?

Answer 11

Auto-antibodies attack Ach receptors within neuromuscular junctions and this prevents Na+ influx and muscle contraction - muscle weakness

Question 12

Describe Goodpasture’s disease?

Answer 12

Auto-antibody against type.IV collagen in the basement membrane of lungs and kidneys = renal failure and haemoptysis

Question 13

Define type 3 hypersensitivity reactions?

Answer 13

Immune-complexes initiate destructive processes resulting in the production of IgG antibodies - IgG/Ag complexes are recognised by complement and cascade is initiated

Question 14

How are immune-complexes transported around the body and how does this process fail sometimes?

Answer 14

Red blood cells via CR1 receptors to the spleen
XS amounts of Ag = serum sickness
Chronic infections
Systemic lupus erythrematous (SLE)

Question 15

Name six clinical features associated with SLE?

Answer 15

Arthralgia
Rash
Arthritis 
Pleurisy 
Pericarditis
Photo-sensitivity

Question 16

Describe the pathogenesis of SLE?

Answer 16

Cell death leads to remnants (self-Ag) up-taken by APC and shown to T-cell = Activates B-cells = Autoimmune antibodies produced = circulating complexes/bid directly to tissues = complement activation = inflammation

Question 17

Describe farmer’s lung?

Answer 17

Inhaled allergens provoke IgG response (as opposed to IgE) and complexes form in alveoli - local fluid accumulates and this results in decreased blood/gas exchange