This invention provides monoclonal antibodies that recognize the Toll-like Receptor 4/MD-2 receptor complex, and monoclonal antibodies that recognize the TLR4/MD2 complex as well as TLR4 when not complexed with MD-2. The invention further provides methods of using the humanized monoclonal antibodies as therapeutics. This invention also provides soluble chimeric proteins, methods of expressing and purifying soluble chimeric proteins, and methods of using soluble chimeric proteins as therapeutics, in screening assays and in the production of antibodies.