What is the Difference Between IgG IgM IgA IgE and IgD?

There are five classes of immunoglobulins (Ig), also known as antibodies, found in serum: IgG, IgM, IgA, IgE, and IgD. They are distinguished by the type of heavy chain they contain and have different functions in the immune system. Here are the main differences between them:

1. IgG (gamma heavy chain):

• Main antibody in blood
• Powerful ability to bind to bacteria and toxins
• Only isotype that can pass through the placenta, providing protection for newborns
• Comprises about 70-75% of the total immunoglobulins in blood

1. IgM (mu heavy chain):

• Exists as a pentamer (five units of basic Y-shaped structures)
• First immunoglobulin made by B cells as they mature
• Mainly distributed to the lymphatic system
• Present on the surface of B cells as the antigen receptor

1. IgA (alpha heavy chain):

• Mainly found in body secretions, such as tears, saliva, respiratory and intestinal secretions, and breast milk
• Exists as monomers in blood but forms dimers in secretions
• Provides protection against infection in mucosal areas of the body
• Comprises about 10-15% of the total immunoglobulins in blood
• Has two subclasses: IgA1 and IgA2

1. IgD (delta heavy chain):

• Present on the surface of most B cells early in their development
• Little IgD is released into circulation
• Role in the immune system is not completely understood

1. IgE (epsilon heavy chain):

• Associated with allergies, allergic diseases, and parasitic infections
• Binds to mast cells and is involved in allergic reactions
• Comprises about 0.5% of the total immunoglobulins in blood

These immunoglobulins play crucial roles in the immune system, protecting the body from various pathogens and allergens.

Comparative Table: IgG IgM IgA IgE vs IgD

Here is a table comparing the differences between IgG, IgM, IgA, IgE, and IgD:

Please note that this table summarizes the main differences between the immunoglobulins, as more complex information can be found in the sources provided.