<prompt> Which among the following is an example for type I hypersensitivity reaction?Casonis testAhus reactionGraves diseasePernicious anemia  <response>: Type I reactions ie, immediate hypersensitivity reactions involve immunoglobulin E IgE-mediated release of histamine and other mediators from mast cells and basophils. Casonis test, intradermal injection of hydatid fluid followed by production of wheal-flare reaction denotes hydatid infection. It is an immediate hypersensitivity reaction Type I. Ahus reaction is a type of local type III hypersensitivity reaction. Type III hypersensitivity reactions are immune complex-mediated, and involve the deposition of antigenantibody complexes. The autoimmune diseases, Myasthenia gravis, Graves disease and Pernicious anemia are examples of Type II hypersensitivity. 