without detectable blast infiltration. At diagnosis of MDS, interface cytogenetic and RT-PCR analyses, respectively, showed trisomy 8 and absence of AF9-MLL rearrangement in Introduction the bone marrow (BM). On readmission with florid leukemia, his peripheral white blood cell count was 13 200/mm 3 , with A subtle, reciprocal translocation exchanging the terminal 56% leukemic blasts. His hemoglobin concentration was short and long arm segments of chromosomes 9 and 11, 15.0 g/dl, and his platelet count was 22 000/mm 3 . The bone respectively t(9;11)(p21-22;q23), is associated with acute marrow aspiration showed 92% leukemic blasts, and the mormyeloid leukemia (AML)-M5, 1 particularly the M5a subtype. 2 phological diagnosis was made as AML-M5a. Cytogenetic Ascertainment may be difficult in suboptimal preparations analysis was interpreted as: 47, XY, +8, t(9;11)(p22;q23). and, despite being regarded as the 'standard' cytogenetic Immunophenotyping analysis of fresh leukemia blasts change in acute monoblastic leukemia, its overall incidence revealed no significant expression of CD antigens associated and pattern of associations remain uncertain. 2 A recent study with the myelo-monocytic lineage. CD34 was 30% positive comparing AML-M1 and -M5 patients, analyzed simuland non-lineage-associated HLA-DR was found to be positive taneously by reverse transcriptase-polymerase chain reaction at 70%; whereas those indicative of lymphoid lineage includ-(RT-PCR), Southern blotting and fluorescence in situ hybridizing CD3, CD4, CD8, CD10, CD19 were absent or weakly ation (FISH) with an MLL-specific yeast artificial chromosome expressed. Myeloperoxidase activity was weakly detected on (YAC) probe, suggests the overall incidence of MLL rearrangethe fresh leukemic blasts. Despite receiving chemotherapy, he ment in AML-M5 may be as high as 60%. 3 It was apparent in succumbed to rapidly progressive leukemia on 15 August that study that approximately half the cases with MLL 1995. rearrangement went undetected by cytogenetic methods, including a cryptic t(6;11)(q27;q23) resulting from a cytogenetically invisible insertion juxtaposing AF6 and MLL.Materials and methods A case of AML-M5a with de novo MLL-AF9 fusion evolving from MDS with trisomy 8 present at all phases has recently Cell culture been described. 4 We describe a pair of cell lines, MOLM-13 During relapse, after chemotherapy, a heparinized peripheral blood specimen, obtained with informed consent, was proCorrespondence: Y Matsuo,

Ryanodine receptor (RYR) is a Ca2+ channel that mediates Ca2+ release from intracellular stores. We have used RT-PCR analysis and examined its expression in primary peripheral mononuclear cells (PBMCs) and in 164 hemopoietic cell lines. In PBMCs, type 1 RYR (RYR1) was expressed in CD19+ B lymphocytes, but less frequently in CD3+ T lymphocytes and in CD14+ monocytes. Type 2 RYR (RYR2) was mainly detected in CD3+ T cells. Induction of RYR1 and/or RYR2 mRNA was found after treatment with stromal cell-derived factor 1, macrophage-inflammatory protein-1α (MIP1α) or TGF-β. Type 3 RYR (RYR3) was not detected in PBMCs. Many hemopoietic cell lines expressed not only RYR1 or RYR2 but also RYR3. The expression of the isoforms was not associated with specific cell lineage. We showed that the RYR-stimulating agent 4-chloro-m-cresol (4CmC) induced Ca2+ release and thereby confirmed functional expression of the RYR in the cell lines expressing RYR mRNA. Moreover, concordant induction of RYR mRNA with Ca2+ channel function was found in Jurkat T cells. In untreated Jurkat T cells, 4CmC (>1 mM) had no effect on Ca2+ release, whereas 4CmC (<400 μM) caused Ca2+ release after the induction of RYR2 and RYR3 that occurred after treatment with stromal cell-derived factor 1, macrophage-inflammatory protein-1α, or TGF-β. Our results demonstrate expression of all three isoforms of RYR mRNA in hemopoietic cells. Induction of RYRs in response to chemokines and TGF-β suggests roles in regulating Ca2+-mediated cellular responses during the immune response.

Summary. 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 k-type multiple myeloma (stage IIIB with hyperammonaemia and hypercalcaemia). The growth of MOLP-5 cells is constitutively dependent on bone marrow stroma (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±Giemsa-stained MOLP-5 cells showed typical plasma cell morphology with abundant cytoplasm and one to three nuclei. The immunoprofile of MOLP-5 corresponds to that seen typically in primary MM cells: positive for cytoplasmic immunoglobulin (Ig) k light chain, CD28, CD29, CD38, CD40, CD44, CD49d, CD54, CD56, CD58, CD71, CD138 and PCA-1; the cells were negative for surface Ig and various other B-cell, T-cell and myelomonocyte-associated immunomarkers. Interleukin 6 (IL-6) receptor mRNA was found in the reverse transcriptase polymerase chain reaction (RT-PCR) analysis. IL-6 and IL-10 could induce 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) chromosome 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 biology of MM.

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