Hemocyanins are proteins that use copper binding sites to bind and transport oxygen in a variety of arthropods and mollusks. Hemocyanin is isolated from the hemolymph of the animals.

Hemocyanin is one of the strongest antigen, used as an immunological reagent and also as a carrier protein for antibody production against antigens. Recent advances in immunology and the role immune system plays in diseases have opened a whole new era of product development activities aimed at developing novel therapeutics which is aimed at teaching the body's immune system to fight diseases like cancer, AIDS, etc. The approach involves the use of highly immunogenic molecule like the hemocyanin for non-specific immunostimulation (NSI) or active specific immunostimulation (ASI) using conjugate vaccines, wherein the tumor (disease) specific antigens are covalently bound to carrier protein like KLH and the product used in human clinical studies. Such products are termed 'vaccines'. BioVision’s KLH subunits powder has major advantages associated with it, in terms of flexibility of use, the choice of buffer in early developmental studies and avoidance of issues associated with reconstitution of dry powder. These subunits are highly pure and have low endotoxin content.