This invention provides hybridoma cell lines producing monoclonal antibodies which inhibit CD14 mediated cell activation. Monoclonal antibodies produced by these cell lines also are provided. The antibodies are useful for the detection of the presence of cell surface and soluble CD14 in a sample. Chimeric and CDR grafted antibodies generated from the above monoclonal antibodies are further provided. Pharmaceutical compositions containing the above biological compositions are provided. These are useful to treat and prevent disorders with CD14 mediated cell activation, such as sepsis.