Question

Which of the following is involved in allergic reactions?
(a) IgA and mast cells
(b) IgG and basophils
(c) IgE and mast cells
(d) IgG and mast cells

Answer 1

Hint: The substances involved in allergic reactions involve protective proteins and effector cells of the innate immune system. They can develop adaptive immunity by antibodies.

Complete answer:
> IgG and mast cells are involved in allergic reactions. An antibody is also called immunoglobulin which is a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen. In order to remove antigen from the body, the antibodies recognize and latch onto them. All immunoglobulins have an equivalent basic molecular structure, consisting of four polypeptide chains. Two of the chains are heavy (H) or large chains and the other two are identical light (L) or smaller chains. Each chain is encoded by different genes and also manufactured separately. There exists five main classes of immunoglobulin—IgG, IgM, IgA, IgD, and IgE. IgG is the most common class present in the largest amounts in blood and tissue fluids. Each IgG molecule consists of the essential four- chain immunoglobulin structure—two from identical H chains and two from identical L chains, and thus in this way, it also carries two identical antigen- binding sites. The immunoglobulin G i.e., IgG is the only class of immunoglobulin classes that is capable of crossing the placenta. In this way, it also provides a point of immune protection to the developing fetus.
> In response to an allergy, IgE is secreted and circulates in the blood and binds to an IgE- specific receptor on the surface of other kinds of immune cells called mast cells and basophils, which are both involved within the acute inflammatory response.
> The IgE-coated cells are sensitized to the allergen at this stage.

So, the right answer is, '(d) IgG and mast cells'.

Note:
> An antibody is also called immunoglobulin which is a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen
> All immunoglobulins have an equivalent basic molecular structure, consisting of four polypeptide chains. Two of H-chain and two of L-chain.
> IgG is the most common class present in the largest amounts in blood and tissue fluids.
> The immunoglobulin G i.e., IgG is the only class of immunoglobulin classes that is capable of crossing the placenta.