Characterization of a new IgGλ myeloma plasma cell line (EJM): a further tool in the investigation of the biology of multiple myeloma

A new IgG lambda myeloma plasma cell line known as EJM was established from a peritoneal effusion from a patient with extramedullary myeloma. The EJM cells have a plasmablastic morphology with abundant rough endoplasmic reticulum and grow in liquid culture with a doubling time of 72 h and a labelling index of 36%. In addition to cytoplasmic IgG lambda, the cells are positive for CD9, 20, 32, 38, 44, 54, 71, 78, MHC Class II DR, DP and DQ. Studies on the control of the cell line proliferation by cytokines have demonstrated stimulation with interleukin 6. In contrast interferon alpha produces marked inhibition of proliferation in doses of greater than 100 units/ml. The culture conditions and the importance of accessory cells and cytokines in supporting myeloma plasma cell growth in vitro are discussed.