Lactate dehydrogenase production and release in a newly established human myeloma cell line

Aggressive multiple myeloma with high serum lactate dehydrogenase (LDH) often has unusual clinical features and is considered to be a distinct clinical entity of multiple myeloma. A myeloma cell line, designated Maska-98, was established from the bone marrow of a patient with aggressive myeloma with extremely high serum LDH that was resistant to conventional chemotherapy. Maska-98 cells had morphological features of immature plasma cells, and immunophenotypic analysis showed that the cells expressed the plasma cell-associated surface antigens including CD38, 49d, and 56, but no T- or B-cell antigens, such as CD2, 3, 4, 8, 19, and 20. Maska-98 cells contained cytoplasmic immunoglobulin (IgG lambda). By utilizing this cell line we demonstrated that the myeloma cells produce and release a large amount of LDH, since (i) abundant LDH was found in the culture supernatant of Maska-98, (ii) immunocytochemical analysis showed that cytoplasm of the cells was strongly stained with anti-LDH monoclonal antibody, and (iii) Maska-98 cells expressed a greater amount of LDH mRNA than the T-cell line TALL-1, as shown by reverse transcription-polymerase chain reaction. As far as we know, there is no report of a myeloma cell line producing excess LDH. Therefore, Maska-98 would provide a novel source for further studies of the pathogenesis of aggressive multiple myeloma with high serum LDH.