There are provided a soluble CD14 antigen which is a novel in vivo protein useful as a marker for diagnosing sepsis and has the following characteristic features 1) to 3):1) a molecular weight of 13±2 kDa when measured by SDS-PAGE under non-reducing conditions2) an amino acid sequence in which the amino acid sequence of SEQ ID NO:1 is present on its N terminal and3) ability to specifically bind to an antibody prepared by using a peptide comprising 16 amino acid residues described in SEQ ID NO:2 for the antigenand a recombinant soluble CD14 fragment.
