A Brief Introduction To Antibody Classes

Fri, 02/26/2010 - 09:29

We at Novus Biologicals have a huge range of monoclonal and polyclonal immunoglobulins on our antibody database, and are constantly developing more. Immunoglobulins comprise a number of different classes, and it’s important you select the right one for your needs. Here, we give a brief run-down of antibody classification.

Antibodies are composed of polypeptide units (monomers). Each unit comprises 2 heavy and 2 light chains (linked H-L on either side of the Y) Each chain has a single V (variable) domain, and the V-pairs form the 2 binding sites of the molecule.

The 5 primary classes are IgG, IgM, IgA, IgD and IgG, identified by the type of H-chain polypeptides they have. The H-chains (called g, μ, a, e and d-chains, respectively) allow the immunoglobulins to function in different types of, and particular stages of, immune response. The peptide sequences responsible for this are found mainly in the Fc fragment of the chain. Immunoglobulin light chains comprise only two types – kappa and lambda chains.

Antibody classes also vary in the number of monomers, or Y-units they have. This affects the valency of the protein and varies between species.

The monomeric IgG is the predominant class in humans. Because of its abundance and antigen specificacy it is the preferred class for immunology research; the majority of immunoglobulins in antibody catalogues are IgG. IgA exists in both monomeric and dimeric forms, and is the second most prevalent class, comprising around 15% of the total serum content. It has a primary defence role against local infections and is thought to prevent passage of antigens, rather than destroy them. IgM, a pantamer, can similarly exist in monomeric form.


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