ESTABLISHMENT OF A CD45-POSITIVE IMMATURE PLASMA-CELL LINE FROM AN AGGRESSIVE MULTIPLE-MYELOMA WITH HIGH SERUM LACTATE-DEHYDROGENASE

A myeloma cell line (KHM-11) was established from the pleural effusion of a patient with IgA-kappa type aggresive myeloma with high serum la ctate dehydrogenase who was extremely resistant to vincristin, adriamy cin and dexamethasone combination therapy (VAD). The morphology of fre sh tumor cells and KHM-11 was plasmablast according to Greipp's criter ia. In addition to the expression of regular plasma cell antigens, CD3 8 and PCA-1, CD45 was found on both fresh cells and KHM-11. Other T- o r B-cell antigens, such as CD2, 4, 8, 19, and 20 were negative. Cytopl asmic immunoglobulin kappa light chain in KHM-11 was found by flowcyto metry. Southern blot analysis revealed that fresh sample and KHM-11 sh ared the same immunoglobulin gene rearrangement. IL-6 was found in the culture supernatant of KHM-11, and this supernatant stimulated the gr owth of this cell line, indicating an IL-6 autocrine mechanism. These findings indicate that KHM-11 is a CD45-positive immature plasma cell line. As far as we know, there is no report of CD45-positive myeloma c ell line. KHM-11 should be a useful tool for understanding not only th e pathogenesis of aggressive multiple myeloma with high LDH but also f or understanding the mechanism which underlies the terminal differenti ation of B-cells.