Hypersensitivity Test Questions | Questions with 100% Correct Answers | Verified | Updated 2023

Which of the following is a description of a type I hypersensitivity reaction? A. Ragweed antigen cross links with IgE on the surface of mast cells, causing release of preformed mediators and resulting in symptoms of an allergic reaction B. Anti-Fy^a from a pregnant woman crosses the placenta and attaches to the Fy^a antigenpositive red cells of the fetus, destroying the red cells C. Immune complex deposition occurs on the glomerular basement membrane of the kidney, leading to renal failure D. Exposure to poison ivy causes sensitized T cells to release lymphokines that cause a localized inflammatory reaction - A Type I immediate hypersensitivity (anaphylactic) responses are characterized by IgE molecules binding to mast cells via the Fc receptor. Cross linking of surface IgE caused by binding of allergens causes the mast cell to degranulate, releasing histamine and other chemical mediators of allergy. Answer B describes a type II reaction; C describes a type III reaction; and D describes a type IV reaction. Harr, Robert R. Medical Laboratory Science Review (Page 103). F.A. Davis Company. Kindle Edition. Why is skin testing the most widely used method to test for a type I hypersensitivity reaction? A. It causes less trauma and is more cost effective than other methods B. It has greater sensitivity than in vitro measurements