In the mid-1950s Frederik Bang found that crab blood contained amoebocyte cells that functioned like aprimitive immune system. This clotting mechanism helps the horseshoe crab fight off infection. Since horseshoe crab blood clots when it comes into contact with certain bacteria and the test is used to detect extremely small amounts of Gram-negative bacteria, which is present everywhere in the natural environment and can be lethal in the human bloodstream. Thus, over a million humans owe their lives to the development of the horseshoe crab test! Until the horseshoe crab test was developed the standard test for bacterial contamination of pharmaceuticals involved injecting rabbits with a sample of the product and then waiting for forty-eight hours to see if a fever developed. In1968 Bang published instructions for how to produce Limulus amoebocyte lysate (LAL) from horseshoe crab blood. Within a decade the FDA replaced the rabbit test the newly developed LAL test.
At the beginning of the LAL industry manufacturers extracted only a portion of a horseshoe crab's blood before returning it to the ocean but they often released specimens far from their native waters and the horseshoe crabs sometimes died during the bleeding process as a result of mishandling or poor shipping methods. Due to government regulations these detrimental practices are now penalized. The FDA now requires that every scalpel, drug, syringe, and flu shot be tested with LAL. The processed blood of a horseshoe crab is worth $15,000 a quart and horseshoe crabs have become a multimillion-dollar industry. Current research suggests that the LAL test may someday be replaced by a genetically engineered version or other biochemical alternative. This synthetic option would help protect the horseshoe crab population.
References:
Sargent, William. Crab Wars: A Tale of Horseshoe Crab, Bioterrorism, and Human Health. Hanover And London: University Press Of New England, 2002.
Hochstein HD, Levin J, Novitsky TJ. The American Horseshoe Crab: Clotting Cells and Limulus Amebocyte Lysate: An Amazing Analytical Tool. Cambridge, MA: Harvard University Press, 2004.
Hochstein HD, Levin J, Novitsky TJ. The American Horseshoe Crab: Clotting Cells and Limulus Amebocyte Lysate: An Amazing Analytical Tool. Cambridge, MA: Harvard University Press, 2004.