Human bone marrow stroma-dependent cell line MOLP-5 derived from a patientin leukaemic phase of multiple myeloma

The novel multiple myeloma (MM) cell line MOLP-5 and its homologous sister cell line B407, a lymphoblastoid cell line (LCL), were established from the peripheral blood of a 71-year-old Japanese patient with Bence-Jones kappa- type multiple myeloma (stage IIIB with hyperammonaemia and hypercalcaemia). The growth of MOLP-5 cells is constitutively dependent on bone marrow stro ma (BST) cells; none of the cytokines tested nor the culture supernatant of the bone marrow stroma cells could support the growth of MOLP-5. Wright-Gi emsa-stained MOLP-5 cells showed typical plasma cell morphology with abunda nt cytoplasm and one to three nuclei. The immunoprofile of MOLP-5 correspon ds to that seen typically in primary MM cells: positive for cytoplasmic imm unoglobulin (Ig) kappa light chain, CD28, CD29, CD38, CD40, CD44, CD49d, CD 54, CD56, CD58, CD71, CD138 and PCA-1; the cells were negative for surface Ig and various other B-cell, T-cell and myelomonocyte-associated immunomark ers, Interleukin 6 (IL-6) receptor mRNA was found in the reverse transcript ase polymerase chain reaction (RT-PCR) analysis. IL-6 and IL-10 could induc e cellular proliferation in shortterm induction experiments. IL-6 or IL-10 production was not detected by specific enzyme-linked immunoabsorbent assay (ELISA). MOLP-5 cells expressed parathyroid hormone-related protein (PTHrP ) at the mRNA level. Cytogenetic analysis showed the typical t(11; 14) chro mosome abnormality. The novel MOLP-5 cell line together with the B407 B-LCL sister line will be useful model systems in the investigation of the biolo gy of MM.