Final answer:
The five classes of antibodies—IgM, IgD, IgG, IgA, and IgE—differ in function and location, with IgM and IgG in the blood, IgA in mucosal areas, IgD on B cells, and IgE in tissues involved in allergic responses.
Step-by-step explanation:
Five Classes of Antibodies and Their Locations
The five classes of antibodies found in humans are IgM, IgD, IgG, IgA, and IgE. Each class has its distinct functions and locations within the body as part of the adaptive immune response.
- IgM: Often the first antibody type produced in response to an infection, found mainly in the blood and lymph fluid.
- IgD: Located primarily on the surface of immature B cells, acting as an antigen receptor.
- IgG: The most abundant type of antibody in body fluids, known for its role in protecting body tissues and also the only antibody that can cross the placenta to provide protection to the fetus.
- IgA: Found in mucous membranes, saliva, tears, and breast milk, playing a crucial role in protecting body surfaces that are exposed to foreign substances.
- IgE: Located mainly in the lungs, skin, and mucous membranes, known for its role in allergic reactions and protection against parasitic infections.