Osteolysis and hypercalcemia are observed in 5-15%, and 10%, respectively, of malignant lymphoma patients during their clinical course. However, both osteolysis and hypercalcemia are uncommon at onset of the disease. We encountered a 24-year-old male non-Hodgkin's lymphoma patient who had multiple osteolytic lesion from the onset of the disease and repeated episodes of hypercalcemia during the clinical course. The patient died with refractory disease. We studied the expression of chemokines which might affect bone resorption using the reverse transcriptase-polymerase chain reaction (RT-PCR) method. Increased expressions of MIP-1alpha, MIP-1beta and RANKL, which are osteoclast-activating factors, were observed in the RNA derived from the patient's lymphoma cells. The secretion of osteoclast-activating factors such as MIP-1alpha by the tumor cells (and/or bone marrow stromal cells) might be involved in the etiology of osteolysis and hypercalcemia in some malignant lymphoma cases.

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Summary.A novel GM-CSF-dependent myeloid cell line, OHN-GM, was established from a patient who developed acute myelogenous leukaemia (AML) as a consequence of myelodysplastic syndrome (MDS). As the patient had previously received cytotoxic chemotherapy for Hodgkin's disease, the MDS and AML were probably related to such therapy. Sequential karyotypic analysis established a del(5q) as the initial cytogenetic abnormality. Additional alterations, including t(10;13)(q24;q14), had developed subsequently during disease progression. Southern blot analysis of OHN-GM cells suggested deletion of one allele of the IRF-1 gene, although no aberrant transcripts were detected. Fluorescence in situ hybridization analysis revealed the deletion of the Rb gene due to the t(10;13)(q24;q14) translocation, and Western blot analysis demonstrated the absence of Rb protein in OHN-GM cells. Finally, the OHN-GM cells exhibited two missense point mutations in highly conserved regions of the p53 gene. These observations suggest that a multistep process, involving alterations of Rb and p53 genes, may have contributed to the patient's disease development and progression. To our knowledge, OHN-GM is the first cell line derived from a therapy-related AML. These cells may aid the investigation of leukaemogenesis as well as the biology of secondary leukaemia.

Summary.A novel human EBV-negative B-cell line, designated DOBIL-6, was established from a patient with nonsecretary myeloma. The DOBIL-6 cell has cytoplasmic g protein and expresses CD19, 20, 38, 45RO, VLA-4 and PCA-1 antigens, but lacks CD10, 45RA and VLA5 antigens. Chromosome analysis showed that DOBIL-6 cells had many complex structural abnormalities, including t(11;14) (q13;q32), which were consistent with that of the fresh tumour cells. Interestingly, abundant interleukin-6 (IL-6) and parathyroid hormone-related protein (PTHrP) accumulated in the culture supernatant of DOBIL-6 cells. Hypercalcaemia and splenomegaly associated with plasma cell proliferations which resulted in the expansion of the light zones in the follicles were observed in DOBIL-6 transplanted nude mice. RT-PCR analysis detected mRNA for PTHrP, and IL-6 as well as its receptor (GP80) in DOBIL-6 cells.Treatment of the DOBIL-6 cells with neutralizing anti-IL-6 antibody inhibited their growth in a dose-dependent manner, whereas the addition of exogenous IL-6 stimulated it in serum-depleted conditions. These findings suggest that both IL-6 and PTHrP are produced in DOBIL-6 cells, and that IL-6 promotes its growth by an autocrine mechanism. Since IL-6 is known to stimulate not only the growth of B-cell neoplasms but also osteoclastic bone resorption by cooperating with PTHrP, this simultaneous production of IL-6 and PTHrP might be synergistically linked and play a role in the development of hypercalcaemia of the patient. The DOBIL-6 cell is a useful tool to clarify the mechanism of hypercalcaemia associated with mature B-cell neoplasms.