Application of cell-free hemolymph of horseshoe crab in antimicrobial drug screening.

Horseshoe crabs are an ancient invertebrate which possesses powerful innate immune defense against microbes. The simplicity, specificity and rapidity of its antimicrobial response have accorded the horseshoe crab as an excellent animal model from which immune responsive tissues may be procured for biomedical research. Such usefulness is exemplified by the extensive application for nearly four decades, of the limulus amebocyte lysate (LAL) for sensitive detection of endotoxin in the medical industry. Apart from the amebocytes, the cell-free hemolymph (CFH) of this arthropod offers a large repertoire of evolutionarily conserved proteins, which are highly sensitive to pathogens. This makes the hemolymph an ideal physiological microenvironment for simulating an in vitro infection. We therefore propose to employ the CFH as a quick and convenient tool for antimicrobial drug screening in vitro. This specific drug screening system also provides further optimization of drug design, and selection of drugs with antioxidant properties. Being an easily accessible natural resource, and allowing high-throughput screening with uniform and reliable data output, the horseshoe crab CFH provides a desirable physiological milieu for drug screening and development.