Production and characterization of monoclonal antibodies to human myeloperoxidase

Monoclonal antibodies (mAbs) against human myeloperoxidase (MPO) have been derived for immunopurifying MPO and immunophenotyping acute leukemias. Eight antibodies were obtained from a fusion of the P3 plasmacytoma cell line with splenic lymphocytes from mice immunized with purified human MPO. Hybridoma supernatant culture fluids were screened for antibody to MPO by an enzyme-linked immunosorbent assay. The specificity of the mAbs was characterized by immunoblotting, immunoprecipitation, and reactivity against various hematopoietic cells, cell lines, and leukemic blast cells. The eight mAbs generated were of the IgG1 isotype. One of these mAbs was successfully used to develop a one-step immunoaffinity chromatographic purification procedure for MPO. Immunoblotting and immunoprecipitation experiments suggested that the eight mAbs were reactive with at least three antigenic determinants on the MPO molecule. Immunofluorescent studies showed that these mAbs reacted specifically with cells of granulocytic-monocytic lineage and were negative with lymphoid cells. Our results suggest that these mAbs should be useful reagents for immunophenotyping hematopoietic cells.