LIMULUS AMEBOCYTE LYSATE

Limulus amoebocyte lysate (LAL) is an aqueous extract of blood cells (amoebocytes) from the horseshoe crab, Limulus polyphemus. LAL reacts with bacterial endotoxin or lipopolysaccharide (LPS), which is a membrane component of Gram negative bacteria. This reaction is the basis of the LAL test, which is used for the detection and quantitation of bacterial endotoxins.The LAL cascade is also triggered by (1,3)-β-D-glucan. Both bacterial endotoxins and (1,3)-β-D-glucan are considered "Pathogen-Associated Molecular Patterns", or PAMPS, substances which elicit inflammatory responses in mammalian systems.

There are three basic LA test methodologies: gel-clot, turbidimetric, and chromogenic. The primary application for LAL is the testing of parenteral pharmaceuticals and medical devices that contact blood or cerebral spinal fluid. In the United States, the FDA has published a guideline for validation of the LAL test as an endotoxin test for such products

The LAL Test
LAL provides significant benefits to each of us. Have you ever had surgery? Have you ever taken an antibiotic? The FDA now requires an LAL test for injectable and intravenous drugs as well as for screening prosthetic devices such as heart valves or hip replacements. LAL is also used to diagnose spinal meningitis and other diseases.

LAL Production
In order to produce LAL, large horseshoe crabs are caught, examined for health, and bled using a stainless steel needle that is inserted into their circulatory system. The crab's blood is centrifuged to separate the amoebocytes from the liquid plasma. The amoebocytes are then freeze-dried and processed for use in the pharmaceutical industry. Horseshoe crabs are not seriously harmed during this process, and studies have indicated that bled horseshoe crabs have a relatively low mortality rate (10%). People in the LAL business carefully monitor their methods to guard their "golden goose." One quart of LAL is worth $15,000!
Three United States companies produce nearly all Limulus Amoebocyte Lysate products used worldwide. Associates of Cape Cod: http://www.acciusa.com/Cambrex: http://www.cambrex.com/default.aspCharles River Endosafe: http://www.criver.com/products/endotoxin/index.html

New Discoveries
Alternatives to LAL are currently being investigated in India (http://www.nio.org) and China. TAL, or Tachypleus amoebocyte lysate, functions similarly to LAL, aiding in the detection of gram-negative bacteria.
Scientists in Singapore are working to clone the toxin-detecting gene in horseshoe crab blood. If the gene can be cloned, LAL derivatives can be prepared without the harvest of horseshoe crabs for blood extraction.