HS II

Question 1

What type of reaction is a type II hypersensitivity reaction?

Answer 1

Antibody mediated, targets cell bound antigens

Question 2

What immunoglobulin is involved in type II HS reactions and how does this cause a reaction?

Answer 2

IgG/IgM antibodies
Bind to cell bound antigens, cause complement activation which damages tissue
-Cell lysis via membrane attack complex
-Neutrophil recruitment C3a/C5a, release of toxins
-Opsonisation C3b
Antibody dependant cytotoxicity

Question 3

Describe the pathophysiology of haemolytic disease of newborn

Answer 3

Rhesus D negative mother becomes sensitised to Rhesus D antigen in first positive pregnancy
Second pregnancy she produces IgG antibodies that cross the placenta and attack fetal blood cells

Question 4

Describe the disease process of haemolytic transfusion reaction

Answer 4

Incompatibility in ABO group/Rhesus D antigen

Host produces IgM antibodies against donor RBCs, causing cell lysis, kidney failure, circulatory collapse

Question 5

Describe the pathophysiology of Graves’ disease

Answer 5

IgG antibodies bind to thyroid stimulating hormone receptors, so thyroid gland produces thyroid hormones, causing hyperthyroidism

Question 6

What are the clinical features of Graves’ disease?

Answer 6

Weight loss
Goiter 
Anxiety/irritability 
Fine hand tremor 
Heat sensitivity

Question 7

How is Graves’ disease treated?

Answer 7

Anti-thyroid - Carbimazole
Radioactive iodine to destroy thyroid cells
Thyroidectomy

Question 8

How long does a type II HS reaction take to develop?

Answer 8

5-12 hours

Question 9

How does Graves’ disease affect pregnancy?

Answer 9

Maternal antibody to thyroid stimulating hormone is IgG so crosses the placenta, causing receptor activation and hyperthyroidism in the baby

Question 10

Describe the pathophysiology of myasthenia gravis

Answer 10

Anti-acetylcholine receptor antibody binds to Ach receptor, impairing neuromuscular signalling

Question 11

Describe the symptoms of myasthenia gravis

Answer 11

Ptosis 
Diplopia 
Dysphagia 
Facial paralysis 
Hoarse voice 
Trouble walking/ lifting objects

Question 12

Describe how myasthenia gravis is treated

Answer 12

Corticosteroids eg prednisolone
Azathioprine for immunosuppression
Thymectomy

Question 13

Describe treatment of type II HS reactions and why this helps

Answer 13

Immune suppression - reduces complement activation
Plasmapheresis - removes circulating antibodies and inflammatory mediators
IV immunoglobulin - promote IgG degredation

Question 14

Describe the pathophysiology of Goodpasture’s syndrome

Answer 14

Anti glomerular basement membrane antibodies bind to GBM, activate compliment pathway, causing cell death