Hypersensitivities - Robison

Question 1

What is type I hypersensitivity?

Answer 1

Allergic reaction- immediate
IgE production which leads to histamine release by mast cells and basophils

Localized: asthma, hay fever, food allergies
Systemic: bee sting, seafood, nuts, penicillin
Autoimmune diseases: autoimmune hemolytic anemia, thrombocytopenia

Treatment: avoidance, immunotherapy, immunosuppressants, anti-IgE

Question 2

What is Type II hypersensitivity?

Answer 2

Cell receptor and cytotoxic hypersensitivity
IgG driven

Reactions like incorrect blood transfusions,
Autoimmune diseases: hemolytic disease of the newborn, graves, myasthenia gravis

Treatments: Rhogam to mother

Question 3

What is type III hypersensitivity?

Answer 3

Immune complex hypersensitivity
Driven by IgG that binds to soluble Ag and can’t be broken down. Neutrophils start to damage tissue

Autoimmune diseases: RA, serum sickness, SLE
Arthur’s reactions: acute localized reaction that occurs with bug bites

Treatment: immunosuppressants

Question 4

What is type IV hyper sensitivities?

Answer 4

Delayed hypersensitivity
Cell mediated and driven by Th1 or Tc
Related to haptens

Poison ivy, contact HS, positive TB test
Autoimmune disease: celiac, Hashimotos, diabetes mellitus, MS

Question 5

What’s are the factors involved in allergenicity?

Answer 5

Allergen, dose, route, adjuvant, genetics of host

Question 6

What is a hapten and what does it do?

Answer 6

A hapten is a small protein
But itself it does not do anything, but combining with a larger protein will induce a hypersensitivity
Presented by MHC II, will activate Th1 cells