Which class of immunoglobulin is the first to be produced in response to an infection?

Correct answer: (c) IgM

Explanation

Immunoglobulins (antibodies) are produced by B cells; the five classes are IgG, IgA, IgM, IgE and IgD.

IgM is the first antibody produced in the primary immune response; as a pentamer it is excellent at agglutination and complement activation.

IgG dominates the secondary response, IgA guards mucosal surfaces, and IgE mediates allergy and anti-parasite defence.