Spontaneous secretion of tumor necrosis factor-beta by human myeloma cell lines

Causal relationship between circulating levels of cytokines and bone mineral density: A mendelian randomization study

BACKGROUND

Numerous studies have shown that various cytokines are important factors affecting bone mineral density (BMD), but the causality between the two remains uncertain.

METHODS

Genetic variants associated with 41 circulating cytokines from a genome-wide association study (GWAS) in 8,293 Finns were used as instrumental variables (IVs) for a two-sample Mendelian randomization (MR) analysis. Inverse variance weighting (IVW) was employed as the primary method to investigate whether the 41 cytokines were causally associated with BMD at five different sites [total body bone mineral density (TB-BMD), heel bone mineral density (HE-BMD), forearm bone mineral density (FA-BMD), femoral neck bone mineral density (FN-BMD), and lumbar spine bone mineral density (LS-BMD)]. Weighted median and MR-Egger were chosen to further confirm the robustness of the results. We performed MR pleiotropy residual sum and outlier test (MR-PRESSO), MR-Egger regression, and Cochran's Q test to detect pleiotropy and sensitivity testing.

RESULTS

After Bonferroni correction, two circulating cytokines had a strong causality with BMD at corresponding sites. Genetically predicted circulating hepatocyte growth factor (HGF) levels and HE-BMD were negatively correlated [β (95 % CI) -0.035(-0.055, -0.016), P=0.00038]. Circulating macrophage inflammatory protein-1α (MIP-1α) levels and TB-BMD were negatively correlated [β(95 %CI): -0.058(-0.092, -0.024), P=0.00074]. Weighted median and MR-Egger results were in line with the IVW results. We also found suggestive causal relationship (IVW P<0.05) between seven circulating cytokines and BMD at corresponding sites. No significant pleiotropy or heterogeneity was observed in our study.

CONCLUSION

Our MR analyses indicated a causal effect between two circulating cytokines and BMD at corresponding sites (HGF and HE-BMD, MIP-1α and TB-BMD), along with suggestive evidence of a potential causality between seven cytokines and BMD at the corresponding sites. These findings would provide insights into the prevention and treatment of osteoporosis, especially immunoporosis.

A dominant-negative F-box deleted mutant of E3 ubiquitin ligase, β-TrCP1/FWD1, markedly reduces myeloma cell growth and survival in mice

Treatment of multiple myeloma with bortezomib can result in severe adverse effects, necessitating the development of targeted inhibitors of the proteasome. We show that stable expression of a dominant-negative F-box deleted (ΔF) mutant of the E3 ubiquitin ligase, SCF^β-TrCP/FWD1, in murine 5TGM1 myeloma cells dramatically attenuated their skeletal engraftment and survival when inoculated into immunocompetent C57BL/KaLwRij mice. Similar results were obtained in immunodeficient bg-nu-xid mice, suggesting that the observed effects were independent of host recipient immune status. Bone marrow stroma offered no protection for 5TGM1-ΔF cells in cocultures treated with tumor necrosis factor (TNF), indicating a cell-autonomous anti-myeloma effect. Levels of p100, IκBα, Mcl-1, ATF4, total and cleaved caspase-3, and phospho-β-catenin were elevated in 5TGM1-ΔF cells whereas cIAP was down-regulated. TNF also activated caspase-3 and downregulated Bcl-2, correlating with the enhanced susceptibility of 5TGM1-ΔF cells to apoptosis. Treatment of 5TGM1 tumor-bearing mice with a β-TrCP1/FWD1 inhibitor, pyrrolidine dithiocarbamate (PDTC), significantly reduced tumor burden in bone. PDTC also increased levels of cleaved Mcl-1 and caspase-3 in U266 human myeloma cells, correlating with our murine data and validating the development of specific β-TrCP inhibitors as an alternative therapy to nonspecific proteasome inhibitors for myeloma patients.

Bone lesions and macrophage inflammatory protein-1 alpha (MIP-1α) in human multiple myeloma

Bone lesions are a prominent feature accompanying multiple myeloma. Elucidation of the mechanisms regulating osteolysis is crucial in achieving a good quality of life, as such patients suffer from bone pain even after achieving improvement of the disease by high-dose chemotherapy. Recent research has revealed that bone lysis in myeloma patients is the result of both inhibited bone formation and enhanced bone destruction. It has been considered that bone absorption is regulated by activation of osteoclasts mediated by osteoclast activating factor (OAF) produced from myeloma cells. Macrophage inflammatory protein-1 alpha (MIP-1a) is a member of the chemokine family, and was originally determined as a soluble factor secreted from activated macrophages. Many candidates for OAF had been proposed and MIP-1a is now considered a major OAF. In this review, the significance of MIP-1a in myeloma bone disease is summarized.

CC-chemokine ligand 20/macrophage inflammatory protein-3α and CC-chemokine receptor 6 are overexpressed in myeloma microenvironment related to osteolytic bone lesions

The expression of the chemokine CC-chemokine ligand 20 (CCL20)/macrophage inflammatory protein (MIP)-3alpha and its receptor CC-chemokine receptor 6 (CCR6) by multiple myeloma (MM) and microenvironment cells and their potential relationship with osteoclast (OC) formation and osteolytic bone lesions in MM patients was investigated in this study. First, we found that MM cells rarely produce CCL20/MIP-3alpha but up-regulate its production by bone marrow (BM) osteoprogenitor cells and osteoblasts in coculture with the involvement of soluble factors as interleukin-1beta and tumor necrosis factor alpha. MM cells also stimulate both CCL20/MIP-3alpha and CCR6 expression by OCs in coculture. Thereafter, we showed that CCL20/MIP-3alpha significantly increases both the number of multinucleated tartrate-resistant acid phosphatase-positive OCs and receptor activator of nuclear factor-kappaB-positive OC progenitor cells similar to CCL3/MIP-1alpha. Finally, we found that blocking anti-CCL20/MIP-3alpha and anti-CCR6 antibodies significantly inhibits MM-induced OC formation. In vitro data were further expanded in vivo analyzing a total number of 64 MM patients. Significantly higher CCL20/MIP-3alpha levels were detected in MM patients versus monoclonal gammopathy of uncertain significance (MGUS) subjects and in MM osteolytic patients versus nonosteolytic ones. Moreover, a significant increase of CCL20/MIP-3alpha-positive osteoblasts in osteolytic MM patients compared with nonosteolytic ones was observed. Interestingly, no significant difference in BM CCL20/MIP-3alpha expression and level was observed between MGUS and nonosteolytic MM patients. Our data indicate that CCL20/MIP-3alpha and its receptor CCR6 are up-regulated in the bone microenvironment by MM cells and contribute to OC formation and osteolytic bone lesions in MM patients.

Establishment and exploitation of hyperdiploid and non-hyperdiploid human myeloma cell lines

The establishment of clinically relevant human myeloma cell lines is central for our understanding of myeloma pathogenesis and development of novel therapies for the disease. Unfortunately, most available lines were generated from extramedullary sites, harbored multiple genetic abnormalities and categorized as non-hyperdiploid. In contrast, hyperdiploid myeloma cell lines, which represent more than 50% of patients, are rare. We established procedures for establishment of stroma-dependent myeloma lines by passaging primary myeloma cells, in severe combined immunodeficient-human (SCID-hu) or SCID-rab mice followed by maintenance in co-culture with stromal cells. We described the establishment and characterization of two hyperdiploid (LD and CF) and two non-hyperdiploid (JB and BN) cell lines. Using our animal models, we also established bortezomib-sensitive and -resistant BN lines. These cell lines were cellularly, phenotypically and molecularly characterized using flow cytometry immunophenotyping, DNA content, G-band and multicolor spectral karyotyping (SKY) and global gene expression profiling. All four cell lines were infected with lentiviral-expressing luciferase for detection of tumour cells at high sensitivity level and for monitoring myeloma growth in co-cultures and in vivo by live animal imaging. These myeloma cell lines and the procedures used for their establishment provide essential tools for studying myeloma biology and therapy.

Angiopoietin-1 and myeloma-induced angiogenesis

Multiple myeloma (MM) is a plasma cell malignancy characterized by an increase of the bone marrow angiogenesis. Angiopoietin-1 (Ang-1) is a critical factor in the regulation of physiological and pathological vessel formation that acts by binding to a specific receptor Tie2 expressed on endothelial cells. Recent evidences indicate that human MM cells produce Ang-1 and up-regulate its receptor Tie2 in bone marrow endothelial cells. An overexpression of Ang-1 has been also found in MM cells as compared to normal plasma cells. The correlation between Ang-1 expression and BM angiogenesis, demonstrated in MM patients, and the inhibitory effect of Tie2 blocking on MM-induced vessel formation suggest that Ang-1 production by MM cells is critically involved in the angiogenic process in MM. In this review we focalize our attention on Ang-1/Tie2 system and its role in MM-induced angiogenesis.

Curcumin (diferuloylmethane) inhibits constitutive and IL-6-inducible STAT3 phosphorylation in human multiple myeloma cells

Numerous reports suggest that IL-6 promotes survival and proliferation of multiple myeloma (MM) cells through the phosphorylation of a cell signaling protein, STAT3. Thus, agents that suppress STAT3 phosphorylation have potential for the treatment of MM. In the present report, we demonstrate that curcumin (diferuloylmethane), a pharmacologically safe agent in humans, inhibited IL-6-induced STAT3 phosphorylation and consequent STAT3 nuclear translocation. Curcumin had no effect on STAT5 phosphorylation, but inhibited the IFN-alpha-induced STAT1 phosphorylation. The constitutive phosphorylation of STAT3 found in certain MM cells was also abrogated by treatment with curcumin. Curcumin-induced inhibition of STAT3 phosphorylation was reversible. Compared with AG490, a well-characterized Janus kinase 2 inhibitor, curcumin was a more rapid (30 min vs 8 h) and more potent (10 micro M vs 100 micro M) inhibitor of STAT3 phosphorylation. In a similar manner, the dose of curcumin completely suppressed proliferation of MM cells; the same dose of AG490 had no effect. In contrast, a cell-permeable STAT3 inhibitor peptide that can inhibit the STAT3 phosphorylation mediated by Src blocked the constitutive phosphorylation of STAT3 and also suppressed the growth of myeloma cells. TNF-alpha and lymphotoxin also induced the proliferation of MM cells, but through a mechanism independent of STAT3 phosphorylation. In addition, dexamethasone-resistant MM cells were found to be sensitive to curcumin. Overall, our results demonstrated that curcumin was a potent inhibitor of STAT3 phosphorylation, and this plays a role in the suppression of MM proliferation.

Proangiogenic properties of human myeloma cells: production of angiopoietin-1 and its potential relationship to myeloma-induced angiogenesis

Patients with multiple myeloma (MM) have increased bone marrow (BM) angiogenesis; however, the proangiogenic properties of myeloma cells and the mechanisms of MM-induced angiogenesis are not completely clarified. The angiopoietin system has been identified as critical in the regulation of vessel formation. In this study we have demonstrated that myeloma cells express several proangiogenic factors, and, in particular, we found that angiopoietin-1 (Ang-1), but not its antagonist Ang-2, was expressed by several human myeloma cell lines (HMCLs) at the mRNA and the protein levels. In a transwell coculture system, we observed that myeloma cells up-regulated the Ang-1 receptor Tie2 in human BM endothelial cells. Moreover, in an experimental model of angiogenesis, the conditioned medium of HMCLs significantly stimulated vessel formation compared with control or vascular endothelial growth factor (VEGF) treatment. The presence of anti-Tie2 blocking antibody completely blunted the proangiogenic effect of XG-6. Finally, our in vitro results were supported by the in vivo finding of Ang-1, but not Ang-2, mRNA and protein expression in purified MM cells obtained from approximately 47% of patients and by high BM angiogenesis in patients with MM positive for Ang-1, suggesting that the angiopoietin system could be involved, at least in part, in MM-induced angiogenesis.

Malignant hematopoietic cell lines: in vitro models for the study of multiple myeloma and plasma cell leukemia

Multiple myeloma (MM) is a neoplasm of a terminally differentiated B-cell. The disease is progressive and always lethal characterized by the slow proliferation of malignant plasma cells in the bone marrow. Much of our current understanding of the biology of MM has been obtained by studying MM-derived cell lines. Human myeloma cell lines were shown to be suitable model systems for use in various fields of the biological sciences. However, it has proved very difficult to establish cell lines from plasma cell dyscrasias. Most reported MM cell lines have been derived from patients with advanced disease and from extramedullary sites. Nevertheless, within the last 20 years more than 100 cell lines have been established. A significant portion of this panel is partially or well characterized with regard to their cell culture, clinical, immunophenotypic, cytogenetic and functional features. Distinct immunoprofiles could be assigned to MM cell lines. All MM cell lines display chromosomal aberrations; in more than 80% of the cell lines analyzed, chromosome 14 band q32 (immunoglobulin heavy chain locus) is affected; the various types of 14q+ chromosomes showed different distributions among the MM cell lines. A large percentage of MM cell lines is constitutively interleukin-6-dependent or responsive to various cytokines. It is important to realize that not every cell line established from a patient with myeloma is a neoplastic cell line. So-called 'myeloma cell lines' have been previously reported and are still widely used which are in reality Epstein-Barr virus (EBV)-positive B-lymphoblastoid cell lines. The presence of the EBV-genome in residual normal B-cells provides them with a selective growth advantage after explantation. In summary, a significant number of authentic and well-characterized MM cell lines has been established and described. The availability of these bona fide MM cell lines is of great importance for the study of the biology, etiology and treatment of the disease.

Human myeloma cells promote the production of interleukin 6 by primary human osteoblasts

Interleukin-6 (IL-6) is an important growth and survival factor for myeloma cells. However, the identity of the cells producing IL-6 in vivo remains unclear. Myeloma cells are found closely associated with sites of active bone turnover, and cells of the osteogenic lineage, including bone marrow osteoprogenitors, osteoblasts and bone lining cells, may therefore be ideally placed to synthesize IL-6. We have examined the possibility that human osteogenic cells may produce IL-6 in response to stimulation by myeloma cells. Primary human osteoblasts (hOBs) were isolated from normal donors, co-cultured with the human myeloma cell lines, JJN-3, RPMI-8226 and NCI-H929, and the amount of IL-6 released was determined by enzyme-linked immunosorbent assay (ELISA). All myeloma cells stimulated a significant increase in the production of IL-6 when cultured with hOBs (P < 0.05). Prior fixation of hOBs completely abrogated release of IL-6 in the co-cultures. In contrast, fixed myeloma cells retained the ability to induce IL-6 production, suggesting that hOBs were the principal source of IL-6. Physical separation of myeloma cells from hOBs using transwell inserts caused a partial inhibition of IL-6 release (P < 0.05), whereas the addition of media conditioned by myeloma cells to cultures of hOBs stimulated a significant increase in IL-6 production (P < 0.05). hOBs secreted greater amounts of IL-6 than human bone marrow stromal cells (hBMSCs) (2.2- to 3.5-fold, P < 0.05), but incubating hBMSCs with dexamethasone to stimulate osteoblastic differentiation resulted in an increase in their ability to produce IL-6 (1.7- to 4. 8-fold, P < 0.05) and to respond to myeloma cells (P < 0.05). These data clearly indicate that cells of the osteoblast lineage release significant amounts of IL-6 in response to stimulation by myeloma cells and may contribute to the IL-6 that promotes the proliferation and survival of myeloma cells in vivo.

Expression of interleukin-1beta and tumour necrosis factor-alpha in plasma cells from patients with multiple myeloma

Interleukin-1beta(IL-1beta) and tumour necrosis factor-alpha (TNF-alpha) are potent bone resorbing cytokines that may contribute to the development of the osteolytic bone disease observed in patients with multiple myeloma (MM). Although these factors have been identified in cultures of bone marrow mononuclear cells isolated from patients, the identity of the cells responsible for producing IL-1beta and TNFalpha remains unclear. Using a sensitive dual-colour fluorescence in situ hybridization (FISH) technique and a two-colour immunofluorescence method we have investigated the expression of the mRNA and protein, for IL-1beta and TNFalpha, by individual bone marrow plasma cells from patients with MM and monoclonal gammopathy of undetermined significance (MGUS). The mRNA for IL-1beta and TNFalpha was identified in all cells expressing the immunoglobulin light chain from all patients with MM and MGUS. However, the IL-1beta protein could not be detected in cytoplasmic light chain positive cells in any of the patients examined. In contrast, the TNFalpha protein was detected in clonal plasma cells from patients with both MM and MGUS. Interestingly, the IL-1beta and TNFalpha mRNA and proteins were readily detected within a small proportion of the non-plasma cells from patients with both MM and MGUS. These data suggest that myeloma cells in vivo are able to produce TNFalpha but not IL-1beta. In addition, a small proportion of accessory cells are likely to be able to contribute to the production of both ILbeta and TNFalpha.

Long-term oral pamidronate treatment inhibits osteoclastic bone resorption and bone turnover without affecting osteoblastic function in multiple myeloma

This study was performed as a cross-sectional substudy to the Danish-Swedish Pamidronate Study, a randomized placebo-controlled multicentre trial in multiple myeloma. The purpose was to evaluate the biological effects of long-term treatment with oral pamidronate 300 mg daily on bone metabolism by using histomorphometry and analysis of cytokines and biochemical markers of bone turnover. Sixteen patients were included after median 27.5 months of protocolized treatment; 10 patients received active treatment and 6 patients placebo. When compared with placebo, pamidronate treatment was associated with: (a) marked decreased osteoclastic resorption rate (0.86+/-0.59 microm/d vs. 5.7+/-5.0 microm/d, p=0.002), and diminished activation frequency (0.20+/-0.18 yr(-1) vs. 0.72+/-0.55 yr(-1), p=0.014); (b) compensatory reduced volume referent bone formation rate (0.17+/-0.21 yr(-1) vs. 0.71+/-0.54 yr(-1), p=0.007), but unaltered mineral appositional rate; (c) neutral (-0.66+/-5.6 mm) vs. negative (-2.15+/-2.2 microm, p=0.013) bone balance per remodelling cycle; (d) higher trabecular bone volume (21.0+/-6.2% vs. 13.0+/-3.7%, p=0.01); (e) suppressed urinary excretion and serum levels of some of the biochemical markers of bone metabolism; and (f) significant reduction of circulating soluble interleukin-6 receptor (IL-6sR) (25.9+/-4.1 ng/ml vs. 32.1+/-6.6 ng/ml, p=0.04), and (g) a uniform tendency of lower serum and marrow plasma levels of IL-6, IL-1beta, and TNFalpha. Thus oral pamidronate was absorbed in biologically active amounts, and reduced overall bone resorption and bone turnover without impairing osteoblastic bone formation. The observation that cytokine and cytokine receptor levels were reduced extends the possible and potential beneficial actions of bisphosphonates in multiple myeloma.

Biochemical bone markers in patients with multiple myeloma

Enhanced bone resorption is a characteristic finding in multiple myeloma (MM). The aim of this study was to assess the newer biochemical bone markers in patients with myeloma. We studied 17 MM patients--10 males (3 untreated, 5 in remission, 2 responding), 7 females (3 in remission, 4 responding) and 15 normal controls. Serum bone specific alkaline phosphatase (BSALP), osteocalcin (OC) and procollagen type 1 C-terminal peptide (PICP) were determined as markers of bone formation, while serum tartrate resistant acid phosphatase (TRAP), urinary deoxypyridinoline (Dpyr) and calcium (Ca) were determined as markers of bone resorption and the ratio of the levels of bone formation/resorption were determined. All markers were measured by enzyme immunoassays (Metra Biosystems), except for TRAP by an in-house enzymatic assay and Ca by the cresolphthalein method. The Dpyr and Ca were expressed as a ratio to urinary creatinine (Cr) excretion. There were significantly higher (i) (Dpyr/Cr)/PICP ratio in male MM patients than in controls (P < 0.05); (ii) (a) urinary Dpyr excretion (P < 0.001), (b) (Dpyr/Cr)/BSALP ratio (P < 0.0001) and (c) (Dpyr/Cr)/PICP (P < 0.0001) in the untreated male MM subgroup than controls; (iii) (Dpyr/Cr)/BSALP ratio (P < 0.05) in the untreated than in the responding male MM subgroup, (iv) (Dpyr/Cr)/PICP ratio (P < 0.05) in untreated male patients than in those in the remission subgroup. In conclusion, (a) Dpyr is a sensitive marker in assessment of bone resorption in MM patients; (b) (Dpyr/Cr)/BSALP or (Dpyr/Cr)/PICP ratio is even more sensitive in distinguishing the untreated from the other MM subgroups and controls. Therefore, the use of a combination of these markers may have a potential role in the management of patients with MM.

Erythropoiesis and erythropoietin in multiple myeloma

In this review, the pathophysiology and treatment of the anemia of multiple myeloma will be examined. While the anemia of cancer has multiple causes, an important component is labeled the "anemia of chronic disease" which is characterized by the combination of a shortened erythrocyte survival with failure of the bone marrow to increase red cell production in compensation. Depressed erythropoiesis is itself related to a combination of factors, including impaired availability of storage iron, inadequate erythropoietin response to anemia, and overproduction of cytokines which are capable of inhibiting erythropoiesis. These cytokines are involved in the retention of iron in the reticuloendothelial system, gastrointestinal tract and hepatocytes, may interfere with erythropoietin production by the kidney, and may exert direct inhibitory effects on erythroid precursors. While overproduction of several such cytokines, including IL-6, IL-1 and TNF-alpha, has been definitely demonstrated in multiple myeloma patients, it is still unclear whether they are directly involved in the pathogenesis of the anemia which develops. Although several mechanisms, such as hemodilution, bleeding, and decreased red cell survival operate, the anemia is mostly caused by defective erythropoietic activity. This in turn is partly explained by inadequate erythropoietin (Epo) production even in some patients without renal impairment. Based on measurements of serum erythropoietin and transferrin receptor, the distinction between marrow unresponsiveness to normal Epo stimulation and deficient Epo production is important for the treatment of the anemia of multiple myeloma with recombinant human Epo. Higher doses would probably be necessary if adequate Epo production is present, whereas only replacement therapy with lower doses may be sufficient when Epo production has been shown to be inappropriate.

TNF and IL-6 are potent growth factors for OH-2, a novel human myeloma cell line

A novel human myeloma cell line, OH-2, was established from pleural fluid of a myeloma patient in end stage of the disease. Effects of cytokines on proliferation were analyzed by measuring uptake of 3H-thymidine. Cell surface antigens were detected by flow cytometry. The cell line is dependent on IL-6 for growth and proliferates in response to TNF. There is synergy between the stimulatory response of TNF and IL-6. The cells express both the p55 and p75 TNF receptors. Neutralizing anti-IL-6 did not inhibit TNF-mediated proliferation, showing that TNF acts through a pathway that is independent of IL-6. TNF was more potent than IL-6 in stimulating the growth of primary myeloma cultures (> 99% pure) from the same patient (OH-2-PC), indicating that TNF in selected myeloma patients has a growth-promoting effect equal to IL-6. OH-2 cells produce and secrete monoclonal IgG-kappa.

Connective tissue components in serum in multiple myeloma: analyses of propeptides of type I and type III procollagens, type I collagen telopeptide, and hyaluronan

The present study was performed to evaluate whether information concerning synthesis and degradation of type I collagen in multiple myeloma (MM) as obtained by serum analyses of C-terminal propeptide of type I procollagen (PICP) and the C-terminal telopeptide of type I collagen (ICTP) may be useful in evaluating the development of osteolytic bone destruction. Serum N-terminal propeptide of type III procollagen (PIIINP) may give information about marrow fibrosis in MM. No data are available about MM and serum hyaluronan, another important component of bone marrow stroma. We examined 15 consecutive patients before treatment and 15 sex- and age-matched controls. We found highly significant elevations in serum ICTP (median 6.2 vs. 2.4 micrograms/L; P < 0.01), PIIINP (median 5.2 vs. 2.9 micrograms/L; P < 0.01) and hyaluronan (median 122 vs. 45 micrograms/L; P < 0.01). ICTP in serum correlated closely to bone morbidity (r = 0.69; P < 0.01). Furthermore, serum ICTP correlated highly significantly to serum PIIINP (P < 0.01) and serum beta 2-microglobulin (P < 0.01), whereas there was no correlation between hyaluronan and any of the collagen-derived peptides or beta 2-microglobulin. The MM group was followed for 9-25 months and analysis of survival data suggested that serum ICTP may be of predictive value (P < 0.05). We conclude that important changes in connective tissue metabolism occur in MM. ICTP in serum seems to be a noninvasive marker of bone morbidity and may be of prognostic value. Furthermore, elevation of hyaluronan in serum is common in MM, the significance of which is unknown.

Lack of IL-1 secretion from human myeloma cells highly purified by immunomagnetic separation

This paper describes a method for purification of human myeloma cells. Mononuclear cells from six bone marrow samples and one pleural fluid sample from multiple myeloma patients were incubated with B-B4, a monoclonal antibody that is specific for plasma cells, and the B-B4+ cells were isolated using monosized magnetic beads coated with sheep anti-mouse Ig. With this positive selection method it was possible to achieve primary cultures with more than 99% myeloma cells. The average viability of these cultures was 81%. The B-B4 antibody did not alter proliferation or cytokine production of the myeloma cell lines U-266 and JJN-3. The B-B4+ myeloma cultures did not produce IL-1 and made only small amounts of IL-6 (< 93 pg/ml), whereas the cells remaining after extraction of the B-B4+ cells produced IL-1 (89-350 pg/ml) and large amounts of IL-6 (520-17,000 pg/ml). This indicates that the B-B4+ myeloma cells are not directly responsible for the overproduction of these cytokines in multiple myeloma. This separation technique gave higher purity of myeloma cells than has been previously reported for any negative selection method and is recommended when high culture purity is of critical interest.

Tumor necrosis factor-beta and hypercalcemia

Hypercalcemia in hematological malignancy is frequently encountered in lymphoid malignancies such as adult T-cell leukemia (ATL) and multiple myeloma and is difficult to manage. As a causative agent of hypercalcemia in ATL, tumor necrosis factor-beta (TNF-beta), previously known as lymphotoxin, has been carefully studied and reviewed here. Bone resorption studies showed the presence of activity in culture supernatants of HTLV-I infected cells. Enzyme linked immunosorbent assays (ELISA) for TNF-beta detected elevated TNF-beta in the sera of ATL patients with hypercalcemia. Immunostaining by monoclonal anti-TNF-beta antibody demonstrated the presence of TNF-beta in both HTLV-I infected cell lines and freshly isolated ATL cells. Furthermore biological TNF-beta activity assay including inhibition of anti-TNF-beta antibody confirmed the conventional documentation of TNF-beta activity in the sera and culture supernatants of HTLV-I infected cell lines. These studies showed that the TNF-beta secreted from ATL cells might be one of the factors contributing to the hypercalcemia in patients with ATL functioning as an osteoclast activating factor (OAF).

Serum osteocalcin concentrations in patients with multiple myeloma--correlation with disease stage and survival

Multiple myeloma affects bone, and enhanced bone resorption is a characteristic finding. In the present study the serum concentration of osteocalcin, serum bone gla-protein, which is a protein specific for bone turnover and reflects osteoblast activity, was analysed at diagnosis in 48 patients with multiple myeloma. At that time there was a significant relationship between disease stage (Durie-Salmon) and osteocalcin levels, lower levels being found in patients with more advanced disease. No relationship was found between osteocalcin and serum calcium levels. To date, 33 patients have died. There was a significant correlation between initial osteocalcin levels and patient survival. These findings suggest that serum osteocalcin could be a marker of prognostic significance for survival in multiple myeloma.

Osteoclast cytomorphometry demonstrates an abnormal population in B cell malignancies but not in multiple myeloma

Increased bone resorption in the vicinity of myeloma cells is mediated by local stimulating factors. Other malignancies of the B cell lineage are also able to produce resorbing factors responsible for increased bone resorption. We have studied three groups of subjects: 10 patients with overt multiple myeloma, 10 patients with a B cell malignancy, and 10 healthy human subjects as controls. Patients were studied at the time of diagnosis and had a transiliac bone biopsy. Osteoclasts were evident on histological sections by their acid phosphatase activity. A software was developed on an automatic image analyzer (Leitz TAS+) for measuring the maximal Feret's diameter (Oc.Le) of each osteoclast (corresponding to the osteoclast length). The histogram of Oc.Le frequency distribution was supplied in each group. In myeloma patients, the Oc.Le frequency distribution was similar to that in normal subjects and showed the histogram to be asymetric with a positive skew (maximum peak at 20-25 microns). With a graphical analysis, this distribution was shown to follow a lognormal distribution corresponding to a homogeneous osteoclast population. In other B cell malignancies, Oc.Le displayed a bimodal distribution with a peak at 20-25 microns and a lower peak at 10-15 microns. The graphical analysis showed that small (mononucleated?) osteoclasts are present in B cell malignancies with normal osteoclasts. This might reflect the secretion of different soluble factors by malignant cells of the B lymphocyte lineage.

Monoclonal gammopathies: new approaches to clinical problems in diagnosis and prognosis

When a patient presents with monoclonal gammopathy, a wide variety of clinical conditions must be considered. The importance of distinguishing accurately between patients with stable monoclonal gammopathies and those with overt multiple myeloma cannot be over-emphasised. The bone marrow examination with plasma cell labeling index, and newer techniques such as magnetic resonance imaging and computed tomography can improve diagnostic discrimination. In difficult cases, the detection of small numbers of circulating myeloma cells, the peripheral blood B-cell labeling index, and light chain isotype suppression may bring better diagnostic resolution. These tests may also be used to help assess disease activity. If the diagnosis is multiple myeloma, prediction of outcome assumes clinical importance. There are widely disparate survivals among patients with different clinical presentations. Standard clinical assays or a combination of these as in clinical staging do not provide sufficient prediction of outcome but are routinely available and therefore widely used. Independent predictive tests such as the plasma cell labeling index and beta 2-microglobulin improve prognostic accuracy. Ploidy analysis and immunophenotyping are additional variables that may assume more importance as the results of ongoing studies appear. Other promising approaches include detection of oncogene and multiple drug resistance gene expression. All such techniques will become more relevant as we apply more intensive treatment earlier in the disease course, particularly for the younger myeloma patients in whom the prognosis is poor.