Which type of immunoglobulin chain is classified as either Kappa or Lambda?

The type of immunoglobulin chain classified as either Kappa or Lambda is the light chain. Immunoglobulins, or antibodies, consist of two types of polypeptide chains: heavy chains and light chains. The light chains can specifically be of two types known as Kappa (κ) and Lambda (λ).

Each immunoglobulin molecule has two light chains, and the choice between Kappa and Lambda chains is determined during B cell development. The distinction between Kappa and Lambda is critical for understanding various immunological functions and for diagnosing certain diseases, such as multiple myeloma, where an increase in one type of light chain can indicate the presence of a specific monoclonal protein.

The heavy chain, on the other hand, does not exhibit this classification and comes in different types (IgA, IgD, IgE, IgG, IgM), which determine the class and overall function of the antibody. The variable chain refers to the region of both heavy and light chains that contributes to the antigen-binding site but is not classified as Kappa or Lambda. The constant chain relates to the part of the heavy chain that remains constant within an immunoglobulin class but does not pertain to the light chain classification.