Question

Immediate hypersensitivity, which results in the release of histamine and other inflammatory substances is mediated by
(a) IgA
(b) IgD
(c) IgE
(d) IgG

Answer 1

Hint: They are a kind of antibody that has only been found in mammals. They’re synthesized by plasma cells. They’re defined by the presence of the epsilon heavy chain. They induce the activation of mast cells and basophils.

Complete answer:
Immediate hypersensitivity is an allergic reaction, which produces through the re-exposure to a particular type of antigen is termed as an allergen. During this reaction, the B-cells are stimulated (by CD4+TH2 cells) to supply IgE antibodies specific to an antigen. During sensitization, the IgE antibodies bind to high-affinity IgE receptors on the surface of tissue mast cells and blood basophils. Mast cells and basophils covered through IgE antibodies are "sensitized". Later disclosure to an equivalent allergen cross-links the destined IgE on sensitized cells, leading to anaphylactic degranulation, which is that the immediate and explosive delivery of pharmacologically active pre-formed mediators from storage granules and compatible synthesis of inflammatory lipid mediators from arachidonic acid; a number of these mediators comprise histamine, leukotriene, and prostaglandin, which act on proteins (e.g., G-protein coupled receptors) present on surrounding tissues. The principal effects of those products are vasodilation and smooth-muscle contraction.

Additional information: The system is an integral part of human protection against disease. The normally protective immune mechanisms can sometimes cause detrimental effects within the host called hypersensitivity reactions.  Hypersensitivity is an inappropriate or exaggerated response to an antigen or an allergen. The normal classification for hypersensitivity reactions is that of Gell and Coombs and is currently the foremost commonly known arrangement.
So, the correct answer is ‘(c) IgE’.

Note: Immediate hypersensitivity is additionally referred to as type I hypersensitivity. The difference between a traditional infectious immune reaction and a kind 1 hypersensitivity response is that in type 1 hypersensitivity, the antibody is IgE rather than IgA, IgG, or IgM. IgE is the last described immunoglobulin, having first been identified in 1966.