The monocytic cell line SKM-1 strongly expresses the myeloperoxidase gene

A newly established human monocytic cell line, SKM-1, showed strong expression of myeloperoxidase mRNA, to the same extent as in HL-60 cells. We studied the cell morphology and myeloperoxidase expression of this cell line, which was established from a patient with myelodysplastic syndrome who had an abnormal chromosome on the upstream region of 17p13. Electron micrographs showed the cells to have a fragile and irregular cell surface. SKM-1 cells were peroxidase-positive. About 60% of myeloperoxidase (MPO) was released to the culture fluid from SKM-1 cells but only a few percent of MPO was released from HL-60 cells into the culture fluid. The predominant mRNA size of SKM-1 myeloperoxidase was 3.3 kb although there was a smaller size as well. Fluorescent in situ hybridization of MPO mRNA showed strong staining in 5% to 10% of SKM-1 cells and of bone marrow cells from patients with myelogenous leukemia, while all cells from HL-60 were positive.