The monoclonal antibody 6G3 reacts highly specific with human natural and recombinant LBP. The antibody cross reacts with LBP of a large series of animal species including: sheep, pig, goat, rabbit, dog, rat, bovine and cynomologous monkey, it does not react with murine and horse LBP. The antibody binds to LBP-LPS complexes whereas it inhibits the interaction of this complex with CD14. LPS binding protein (LBP) is an approximately 60 kDa acute phase protein that is produced by hepatocytes. This protein strongly binds to LPS and has been shown to play an important role in the handling of LPS by the host. A number of functions of LBP have been reported. First, LBP transfers LPS to the LPS receptor CD14 on mononuclear phagocytes, leading to an 100-1,000 fold increased sensitivity of the cells to LPS. Furthermore, LBP can enhance the response of CD14 negative cells by acceleration of LPS binding to soluble CD14, a complex that stimulates these cells. Next, LBP transfers LPS into High Density Lipoprotein (HDL), which effectively neutralizes its biological potency. LBP was demonstrated to protect mice from septic shock caused by LPS or gram negative bacteria.