Slotted snail hemocyanin

A large California keyhole limpet (right) from which the KLH is obtained (left in the picture: a sea cucumber)

Slotted snail hemocyanin ( KLH abbreviation , from Keyhole Limpet Hemocyanin ) is a high-molecular protein complex obtained from the hemolymph of the great California keyhole limpet ( Megathura crenulata ) from the family of slotted snails ( Fissurellidae , English keyhole limpets ). With a molecular mass of 8 to 32 million Daltons, KLH is one of the largest known proteins. Hemocyanins are the oxygen- transporting proteins of various molluscs and arthropods that appear blue due to copper atoms .

use

In order to be able to act as an antigen , low molecular weight molecules such as peptides , amino acids , nucleic acids , certain toxins or drugs have to be coupled to carrier proteins (often referred to as “carriers” in the literature ). In addition to ovalbumin (chicken egg albumin) and bovine or human serum albumin , the snail protein KLH is a carrier protein that is widely used in biotechnology for the immunization of animals. In most cases, the hapten is coupled to the carboxyl or amino group of the carrier protein. Binding to carbohydrate residues or the formation of disulfide bridges is also possible. Due to the coupling to KLH, molecules that are otherwise not or only slightly immunologically reactive, the so-called haptens , are presented to the immune system of the immunized animals as fully-fledged antigens. In this way it is only possible to obtain antibodies against these molecules, but the polyclonal immune serum obtained from the blood of the immunized animals contains not only hapten-specific antibodies, but also those that are directed against antigenic determinants of the KLH carrier molecule, as well as a large number of other antibodies that can be traced back to natural antigen contact of the animals. The increase in the immunogenicity of a hapten is brought about by the size of the hapten-KLH conjugation complex and the strong immunogenicity inherent in KLH.

KLH elicits a strong immune response in vertebrates , both cellular and humoral . In medicine, KLH is therefore used as a non-specific modulator ( immune stimulator ), with the help of which the immune competence of a body can be determined.

The immunocyanin is obtained from the native KLH by splitting it into smaller, chemically and physically stable subunits of around 400 kD . Immunocyanin is approved as a drug in the Netherlands, Austria and South Korea for reducing the frequency of recurrence of bladder cancer after surgical removal of the tumor through the urethra ( transurethral resection , TUR). To do this, the freeze-dried medicinal substance is dissolved and introduced into the previously emptied urinary bladder. Immunocyanin is supposed to activate the cellular and humoral immune defense in the bladder mucosa.

Furthermore, immunocyanin is used as a potentiator ( adjuvant ) in immunological research.

Individual evidence

1. ^ Whisnant CC (1989). Production and Evaluation of Polyclonal and Monoclonal Antibodies . in: Fitzpatrick, SC, O'Rangers A, Newkirk, D (Eds). Workshop on screening methods for veterinary drugs in natural contaminants in food animal production. Washington DC. P. 7
2. ↑ ^{a b} Product information from the manufacturer biosyn , accessed September 7, 2009 (restricted access)
3. ↑ Specialist information Immucothel, as of August 2009