Keyhole limpet hemocyanin

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Keyhole limpet hemocyanin (KLH) is a large, multisubunit, oxygen-carrying glycoprotein found in the hemolymph of the keyhole limpet (Megathura crenulata). KLH is widely used in biomedical research and immunology due to its strong immunogenicity and ability to stimulate the immune system.

Structure and Function

KLH is a member of the hemocyanin family, which are copper-containing proteins that transport oxygen in the hemolymph of various mollusks and arthropods. Unlike hemoglobin, which uses iron to bind oxygen, hemocyanins use copper, giving the hemolymph a blue color when oxygenated. KLH is composed of multiple subunits, each with a molecular weight of approximately 350-390 kDa, forming a large, cylindrical structure.

Applications in Research

KLH is extensively used as a carrier protein in vaccine development and as an immunological adjuvant. Its high molecular weight and complex structure make it an effective carrier for haptens, small molecules that are not immunogenic by themselves. When conjugated to KLH, these haptens can elicit a strong immune response, making KLH valuable in the production of antibodies.

Immunotherapy

KLH is used in cancer immunotherapy as a component of cancer vaccines. It helps to enhance the body's immune response against tumor antigens, potentially improving the effectiveness of the vaccine.

Diagnostic Use

In diagnostic immunology, KLH is used as a standard antigen in various immunoassays to evaluate the immune response in experimental settings. It serves as a model antigen to study the mechanisms of antigen presentation and T-cell activation.

Production and Purification

KLH is harvested from the hemolymph of the keyhole limpet, which is native to the coastal waters of California. The purification process involves several steps, including centrifugation, filtration, and chromatography, to ensure the protein is free from contaminants and suitable for research and clinical use.

Safety and Regulatory Status

KLH is generally considered safe for use in humans and animals. It has been used in numerous clinical trials and is approved for use in certain therapeutic and diagnostic applications. However, as with any biological product, there is a potential for allergic reactions and other side effects.

See Also

• Hemocyanin
• Immunology
• Vaccine
• Antibody
• Cancer immunotherapy
• Antigen presentation