Taishi Yamashita

Marrow stromal cells induce B7-H1 expression on myeloma cells, generating aggressive characteristics in multiple myeloma.

Tumor-associated B7-H1 molecules inhibit antitumor immunity in some malignancies. We found that B7-H1 expression on patient myeloma cells and human myeloma cell lines (HMCLs) was upregulated by cultivating the cells with autologous stromal cells and the human stromal cell line HS-5. Among major cytokines produced by HS-5 cells, interleukin (IL)-6-induced B7-H1 expression on HMCLs. Moreover, HS-5 cell-mediated B7-H1 expression was downregulated by inhibiting IL-6. B7-H1+ HMCLs were more proliferative and less susceptible to antimyeloma chemotherapy compared with B7-H1− HMCLs. Moreover, the former cells showed higher levels of Bcl-2 and FasL expression than the latter. Finally, B7-H1 molecules on HMCLs induced T-cell apoptosis and anergy of tumor-specific T cells. Consistent with these in vitro observations, patients whose myeloma cells expressed high levels of B7-H1 had higher myeloma cell percentages in the bone marrow (BM) and higher serum lactate dehydrogenase levels compared with other myeloma patients. In addition, B7-H1 expression levels were often upregulated after myeloma patients relapsed or became refractory to therapy. Our data indicate that the BM microenvironment upregulates B7-H1 expression on myeloma cells, which links to the two biological actions of inducing T-cell downregulation and enhancing aggressive myeloma-cell characteristics. Modulating the B7-H1 pathway may be worthwhile in myeloma.

Interferon-γ and tumor necrosis factor-α induce an immunoinhibitory molecule, B7-H1, via nuclear factor κB activation in blasts in myelodysplastic syndromes

During disease progression in myelodysplastic syndromes (MDS), clonal blasts gain a more aggressive nature, whereas nonclonal immune cells become less efficient via an unknown mechanism. Using MDS cell lines and patient samples, we showed that the expression of an immunoinhibitory molecule, B7-H1 (CD274), was induced by interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) on MDS blasts. This induction was associated with the activation of nuclear factor-kappaB (NF-kappaB) and nearly completely blocked by an NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC). B7-H1(+) MDS blasts had greater intrinsic proliferative capacity than B7-H1(-) MDS blasts when examined in various assays. Furthermore, B7-H1(+) blasts suppressed T-cell proliferation and induced T-cell apoptosis in allogeneic cocultures. When fresh bone marrow samples from patients were examined, blasts from high-risk MDS patients expressed B7-H1 molecules more often compared with those from low-risk MDS patients. Moreover, MDS T cells often overexpressed programmed cell death 1 (PD-1) molecules that transmit an inhibitory signal from B7-H1 molecules. Taken together, these findings provide new insight into MDS pathophysiology. IFNgamma and TNFalpha activate NF-kappaB that in turn induces B7-H1 expression on MDS blasts. B7-H1(+) MDS blasts have an intrinsic proliferative advantage and induce T-cell suppression, which may be associated with disease progression in MDS.

Interferon-gamma and tumor necrosis factor-alpha induce an immunoinhibitory molecule, B7-H1, via nuclear factor-kappaB activation in blasts in myelodysplastic syndromes.

During disease progression in myelodysplastic syndromes (MDS), clonal blasts gain a more aggressive nature, whereas nonclonal immune cells become less efficient via an unknown mechanism. Using MDS cell lines and patient samples, we showed that the expression of an immunoinhibitory molecule, B7-H1 (CD274), was induced by interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) on MDS blasts. This induction was associated with the activation of nuclear factor-kappaB (NF-kappaB) and nearly completely blocked by an NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC). B7-H1(+) MDS blasts had greater intrinsic proliferative capacity than B7-H1(-) MDS blasts when examined in various assays. Furthermore, B7-H1(+) blasts suppressed T-cell proliferation and induced T-cell apoptosis in allogeneic cocultures. When fresh bone marrow samples from patients were examined, blasts from high-risk MDS patients expressed B7-H1 molecules more often compared with those from low-risk MDS patients. Moreover, MDS T cells often overexpressed programmed cell death 1 (PD-1) molecules that transmit an inhibitory signal from B7-H1 molecules. Taken together, these findings provide new insight into MDS pathophysiology. IFNgamma and TNFalpha activate NF-kappaB that in turn induces B7-H1 expression on MDS blasts. B7-H1(+) MDS blasts have an intrinsic proliferative advantage and induce T-cell suppression, which may be associated with disease progression in MDS.

Prognostic significance of WT1 mRNA and anti-WT1 antibody levels in peripheral blood in patients with myelodysplastic syndromes

Wilms tumor gene (WT1) mRNA expression in peripheral blood cells was examined in 80 patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) transformed from MDS. Serum anti-WT1 antibody titers were also determined in 45 patients. Their long-term follow-up showed that the survival rate became worse as the WT1 mRNA level increased. In particular, a high WT1 mRNA level was a strong predictor of a short time to AML transformation even if adjusted by the International Prognostic Scoring System category. Moreover, high values of anti-WT1 antibody were an independent predictor of longer survival. These data may justify therapeutic strategies targeting WT1 molecules in MDS.

Functional B7.2 and B7-H2 Molecules on Myeloma Cells Are Associated with a Growth Advantage

Purpose: B7 family molecules expressed on antigen-presenting cells stimulate or inhibit normal immune responses. The aim of this study was to investigate whether functional B7.2 and B7-H2 molecules are expressed on myeloma cells and, if so, whether they are associated with pathophysiology in myeloma. Experimental Design: The expression of B7.2 and B7-H2 molecules on normal plasma and neoplastic (myeloma) plasma cells was analyzed. The cell proliferation and immunomodulatory function of myeloma cells related to B7.2 and B7-H2 expression were examined. Results: Human myeloma cell lines commonly expressed B7.2 and B7-H2 molecules. B7.2 expression on plasma cells was more common in myeloma patients (n = 35) compared with that in patients with monoclonal gammopathy of unknown significance (n = 12) or hematologically normal individuals (n = 10). Plasma cells expressing B7-H2 were observed in myeloma patients alone, although rarely. Patients whose myeloma cells showed high B7.2 expression were more anemic and thrombocytopenic than other myeloma patients. The expression of these molecules was induced or augmented by cultivating myeloma cells with autologous stroma cells or tumor necrosis factor-α, a key cytokine in myeloma biology. Cell proliferation was more rapid in the B7.2+ and B7-H2+ populations compared with the B7.2− and B7-H2− populations, respectively, in the human myeloma cell lines examined. B7.2 and B7-H2 molecules on myeloma cells induced normal CD4+ T cells to proliferate and produce soluble factors, including interleukin-10 that stimulate myeloma cell proliferation. Conclusions: Functional B7.2 and B7-H2 molecules detected on myeloma cells may be involved in the pathophysiology of myeloma.

Aggressive characteristics of myeloblasts expressing CD7 in myelodysplastic syndromes.

Clinical data suggest that CD7+ myeloblasts are linked with poor prognosis in myeloid malignancies including myelodysplastic syndromes (MDS). To explore the biology behind this, we compared cell characteristics between CD34+CD7+ and CD34+CD7- myeloblasts from an MDS cell line and fresh samples from MDS patients. Compared with CD34+CD7- myeloblasts, CD34+CD7+ myeloblasts showed greater proliferative capacity, more active cell cycling, and less apoptosis. In analyses of a cell line, CD34+CD7+ myeloblasts produced CD34+CD7- myeloblasts and showed lower expressions of interleukin-8 and chemokine (C-C motif) ligand 2 genes, suggesting immaturity of these cells. These findings might underlie the clinical aggressiveness in CD7+ MDS.

Pure White Cell Aplasia : Report of the First Case Associated with Primary Biliary Cirrhosis

Pure white cell aplasia (PWCA) is a rare hematologic disorder characterized by agranulocytosis, a lack of virtually all neutrophil-lineage cells (from neutrophils to myeloblasts) in the bone marrow, and normal erythropoiesis and megakaryocy-topoiesis. We report the first case of PWCA that developed in a patient with primary biliary cirrhosis (PBC). An 83-year-old woman, who had had an elevated serum alkaline phosphatase level and shown positivity for serum antimitochondrial antibodies for 10 years, was referred to us because of a perianal abscess. She had severe neutropenia, and her bone marrow showed typical findings of PWCA. Although methylprednisolone pulse therapy induced complete neutrophil recovery, this effect was transient. She died of infection, and the autopsy confirmed the diagnosis of PBC. In vitro investigations showed that factors inhibitory to normal CD34 cell-derived granulopoiesis were present in the patient’s serum. Int J Hematol. 2007;85:97-100. doi: 10.1532/IJH97.06018