Horseshoe Crab Hemocyte- Derived Lectin Recognizing Specific 0-Antigens of Lipopolysaccharides

In the Japanese horseshoe crab, Tachypleus tridentatus, one of the major defense systems is carried by hemolymph that contains granular hemocytes comprising 99% of the total hemocytes. These granular hemocytes are filled with two populations of secretory granules, named large (L) and small (S) granules. These granules selectively store defense molecules, such as clotting serine protease zymogens, a clottable protein coagulogen, protease inhibitors, lectins, and antimicrobial peptides (1–3). The hemocytes are highly sensitive to LPS and these defense molecules stored in both granules are secreted by exocytosis after stimulation with LPS. This response is important for the host defense related to engulfing and killing invading microbes, in addition to preventing the leakage of hemolymph.