Britannica
Sources used in this answer
Which five main classes of immunoglobulins are produced by B cells?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
antibody
The four-chain structure of an antibody, or immunoglobulin, molecule. The basic unit is composed of two identical light (L) chains and two identical heavy (H) chains, which are held together by disulfide bonds to form a flexible Y shape. Each chain is composed of a variable (V) region and a constant (C) region.
B cells produce five main classes of immunoglobulins, which are categorized based on the structural variations of their heavy (H) chains. These classes are:12
- IgG: The most common class of antibody, primarily found in the blood and tissue fluids.13
- IgM: Often existing as a pentamer, this class is typically the first to be produced during an immune response.3
- IgA: Found predominantly in body secretions such as saliva, tears, and mucus, where it plays a key role in protecting mucosal surfaces.415
- IgD: Detected in much smaller amounts in immune sera compared to other classes.3
- IgE: Also present in smaller amounts, this class is notably involved in allergic responses and defense against parasites.53
Each of these classes possesses distinct biological properties and functions determined by their specific constant regions.162