Monoclonal antibody WGM1 directed against proteinase 3: An immunohistochemical marker for naphthol ASD chloroacetate

Enzyme histochemistry for naphthol ASD chloroacetate (NASDCA, 'Leder's stain') is used to identify the granulocyte lineage ranging from promyelocytes to mature neutrophils and is an additional tool for the characterization of leukemias. We demonstrated for the first time that NASDCA activity can be detected by routine immunohistochemistry and immunocytochemistry using the monoclonal antibody WGM1 directed against proteinase 3 (PR3; synonyms: Wegener's autoantigen, myeloblastin). Immunohisto- and immunocytochemical staining with WGM1 against PR3 and enzyme histochemistry for NASDCA produced identical staining patterns in normal myelomonocytic cells and cells of myeloid leukemia. This was additionally proven by double immunostainings. We have also shown that PR3 is one of the specific proteinases responsible for hydrolysis of NASDCA.