Allergy

Question 1

What are the four types of Hypersensitivity?

Answer 1

Type I: Classical allergy, mediated by the inappropriate production of specific IgE antibodies to harmless antigens
Type II: Caused by IgG and IgM antibodies that bind to antigens cells or tissues leading to cell or tissue damage
Type III: Caused by antibody-antigen complexes being deposited in tissues, where they activate the complement system and cause inflammation
Type IV: A delayed type hypersensitivity reaction caused by T helper cells traveling to the site of antigens, recruiting macrophages and causing inflammation

Question 2

IgE mediated allergy is responsible for a number of atopic conditions: what conditions?

Answer 2

Food or drug allergy
Asthma
Allergic rhinitis
Hayfever
Eczema

Question 3

Name 3 Type 2 Hypersensitivities?

Answer 3

Blood transfusion reactions: When blood is transfused and the ABO group of the donor does not match the recipient, the antibodies in the recipients blood attack the donors blood causing haemolysis of the donor red blood cells, rapidly releasing the contents of those cells and causing a toxic reaction.

Haemolytic Disease of the Newborn: When a rhesus negative mother has a rhesus positive baby, exposure to the babies blood during birth will cause the mother to produce IgG to rhesus. If she has another rhesus positive baby, that IgG will cross the placenta into the babies bloodstream and cause haemolysis of the babies red blood cells.

Goodpastures Syndrome: antibodies specific to a type of collagen in the the glomerular basement membrane in the kidneys and lungs lead to inflammation and destruction of the basement membrane leading to pulmonary haemorrhage and kidney failure.