Deletion of chromosome arm 15q in a case of minimally differentiated hypoplastic AML-M0.

Deletion of the long arm of chromosome 15 is known as a rare but recurrent chromosomal abnormality in myeloid malignancies. We report a novel case of minimally differentiated hypoplastic acute myeloid leukemia (AML M0) in a patient who initially had a normal karyotype, but clonal interstitial deletion of chromosome 15, del(15)(q11.2q22), coincided with increment of leukemic cells a year later. We also summarize 18 published cases with myeloid malignancies and this chromosomal abnormality.

Hematopoietic origin of hepatic stellate cells in the adult liver.

Hepatic stellate cells are believed to play a key role in the development of liver fibrosis. Several studies have reported that bone marrow cells can give rise to hepatic stellate cells. We hypothesized that hepatic stellate cells are derived from hematopoietic stem cells. To test this hypothesis, we generated chimeric mice by transplantation of clonal populations of cells derived from single enhanced green fluorescent protein (EGFP)-marked Lin(-)Sca-1(+)c-kit(+)CD34(-) cells and examined the histology of liver tissues obtained from the chimeric mice with carbon tetrachloride (CCl(4))-induced injury. After 12 weeks of CCl(4) treatment, we detected EGFP(+) cells in the liver, and some cells contained intracytoplasmic lipid droplets. Immunofluorescence analysis demonstrated that 50% to 60% of the EGFP(+) cells were negative for CD45 and positive for vimentin, glial fibrillary acidic protein, ADAMTS13, and alpha-smooth muscle actin. Moreover, EGFP(+) cells isolated from the liver synthesized collagen I in culture. These phenotypes were consistent with those of hepatic stellate cells. The hematopoietic stem cell-derived hepatic stellate cells seen in male-to-male transplants revealed only one Y chromosome. Our findings suggest that hematopoietic stem cells contribute to the generation of hepatic stellate cells after liver injury and that the process does not involve cell fusion.

Notch ligand Delta-1 differentially modulates the effects of gp130 activation on interleukin-6 receptor alpha-positive and -negative human hematopoietic progenitors.

Interleukin (IL)-6 plays pleiotropic roles in human hematopoiesis and immune responses by acting on not only the IL-6 receptor-alpha subunit (IL-6Ralpha)(+) but also IL-6Ralpha(-) hematopoietic progenitors via soluble IL-6R. The Notch ligand Delta-1 has been identified as an important modulator of the differentiation and proliferation of human hematopoietic progenitors. Here, it was investigated whether these actions of IL-6 are influenced by Delta-1. When CD34(+)CD38(-) hematopoietic progenitors were cultured with stem cell factor, flt3 ligand, thrombopoietin and IL-3, Delta-1, in combination with the IL-6R/IL-6 fusion protein FP6, increased the generation of glycophorin A(+) erythroid cells but counteracted the effects of IL-6 and FP6 on the generation of CD14(+) monocytic and CD15(+) granulocytic cells. Although freshly isolated CD34(+)CD38(-) cells expressed no or only low levels of IL-6Ralpha, its expression was increased in myeloid progenitors after culture but remained negative in erythroid progenitors. It was found that Delta-1 acted in synergy with FP6 to enhance the generation of erythroid cells from the IL-6Ralpha(-) erythroid progenitors. In contrast, Delta-1 antagonized the effects of IL-6 and FP6 on the development of monocytic and granulocytic cells, as well as CD14(-)CD1a(+) dendritic cells, from the IL-6Ralpha(+) myeloid progenitors. These results indicate that Delta-1 interacts differentially with gp130 activation in IL-6Ralpha(-) erythroid and IL-6Ralpha(+) myeloid progenitors. The present data suggest a divergent interaction between Delta-1 and gp130 activation in human hematopoiesis.

IL-3 can not replace GM-CSF in inducing human monocytes to differentiate into Langerhans cells.

Receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) share a common beta subunit. We recently reported that GM-CSF acts in concert with transforming growth factor-beta1 (TGF-beta1) and Notch ligand Delta-1 (Delta-1) to promote the differentiation of human blood monocytes into Langerhans cells. In the present study, we examined whether IL-3, in place of GM-CSF, can induce the development of Langerhans cells from blood monocytes in the presence of TGF-beta1 and Delta-1, because the IL-3 receptor alpha chain was substantially expressed on monocytes. However, the generation of Langerhans cells was not obtained by the combination of IL-3, TGF-beta1 and Delta-1, even though GM-CSF and IL-3 exhibited a similar effect with respect to the differentiation of monocytes into macrophages and dendritic cells. The addition of GM-CSF to the culture supplemented with IL-3, TGF-beta1 and Delta-1 restored the differentiation of monocytes toward Langerhans cells. A microarray analysis revealed that a number of genes including Langerhans cell markers, E-cadherin and Langerin, were specifically expressed in cells from GM-CSF-containing cultures but not in those from IL-3-containing cultures. These data suggest that IL-3 can not replace GM-CSF to induce the differentiation of human monocytes into Langerhans cells in culture.

Development of mixed-type autoimmune hemolytic anemia and Evans' syndrome following chicken pox infection in a case of low-titer cold agglutinin disease.

We describe a patient with low-titer cold agglutinin disease (CAD) who developed mixed-type autoimmune hemolytic anemia (AIHA) and idiopathic thrombocytopenia following chicken pox infection. At least 1 year before admission to hospital, the patient had mild hemolytic anemia associated with low-titer cold agglutinins. A severe hemolytic crisis and thrombocytopenia (Evans' syndrome) occurred several days after infection with chicken pox, and the patient was referred to our hospital. Serological findings revealed the presence of both cold agglutinins and warm-reactive autoantibodies against erythrocytes, and the diagnosis was mixed-type AIHA. Following steroid therapy, the hemoglobin (Hb) level and platelet count improved. The patient was closely followed over a 10-year period with recurrent documented hemolysis after viral or bacterial infections. Warm-reactive autoantibodies have not been detected in the last 2 years, and only the immunoglobulin M anti-I cold agglutinins with a low titer and wide thermal amplitude have remained unchanged. Therefore, the patient has received at least 10 mg prednisolone daily to maintain a Hb level of 10 g/dL. To the best of our knowledge, no adult case of low-titer CAD that has evolved into mixed-type AIHA and Evans' syndrome after chicken pox infection has been previously reported in the literature.

Pleiotropic role of histone deacetylases in the regulation of human adult erythropoiesis.

Histone acetylation and deacetylation play fundamental roles in transcriptional regulation. We investigated the role of histone deacetylases (HDACs) in human adult haematopoiesis, using the structurally distinct HDAC inhibitors FK228 (depsipeptide) and Trichostatin A. When CD34+ cells were cultured with interleukin (IL)-3 or stem cell factor (SCF) + IL-3, FK228 (0.5 ng/ml) specifically enhanced the generation of immature erythroid cells with a CD36+ glycophorin A (GPA)low phenotype. In semisolid cultures, FK228 promoted the formation of erythroid colonies by CD34+ cells with IL-3 and SCF + IL-3. Furthermore, upon exposure to FK228, CD34+ cell-derived CD36+ GPA- cells were induced to form erythroid colonies with IL-3 alone. Conversely, FK228 inhibited the generation of CD36+ GPAhigh relatively mature erythroid cells from CD34+ cells in the presence of erythropoietin (EPO) and SCF + EPO. FK228 suppressed the EPO-mediated survival of CD36+ GPAlow/- and CD36+ GPAhigh cells and induced their apoptosis. Similar effects were observed for trichostatin A in the generation of erythroid cells in IL-3- and EPO-containing cultures. These data suggest that HDACs negatively regulate the IL-3-mediated growth of early erythroid precursors by suppressing their responsiveness to IL-3, while playing an important role in EPO-mediated differentiation and survival of erythroid precursors. Our data revealed that HDACs have diverse functions in human adult erythropoiesis.

A putative role for histone deacetylase in the differentiation of human erythroid cells.

Histone acetylation controls the expression of specific genes in eukaryotic cells. We investigated the role of histone deacetylases (HDACs) in the differentiation of human erythroid cells, using pharmacological approaches. When CD36+ erythroid precursor cells, generated from CD34+ cells with stem cell factor, flt-3 ligand, thrombopoietin, interleukin-3, interleukin-6, and erythropoietin, were cultured with an HDAC inhibitor FK228 (depsipeptide) at a specified dose in the presence of erythropoietin, their differentiation was inhibited, as determined by the expression of CD45 and glycophorin A. Addition of the same dose of FK228 to cultures did not affect the growth of CD36+ cells. Regardless of the presence or absence of FK228, cultured CD36+ cells displayed similar proliferation kinetics. Analysis of acetylated histones revealed that FK228 upregulated the acetylation status of histones H3 and H4 in CD36+ cells. The inhibition of CD36+ cell differentiation was restored by removal of FK228 from the culture, indicating that the modification of CD36+ cell differentiation by FK228 is reversible. Furthermore, interference with histone deacetylation by FK228 inhibited the generation of CD36+ erythroid cells from CD34+ hematopoietic progenitor cells. Our results indicate the possible involvement of HDACs in human erythropoiesis, especially the regulation of erythroid cell differentiation.

A novel role for Notch ligand Delta-1 as a regulator of human Langerhans cell development from blood monocytes.

Human Langerhans cells (LCs) are of hematopoietic origin, but cytokine regulation of their development is not fully understood. Notch ligand Delta-1 is expressed in a proportion of the skin. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor-beta1 (TGF-beta1) are also secreted in the skin. We report here that Delta-1, in concert with GM-CSF and TGF-beta1, induces the differentiation of human CD14(+) blood monocytes into cells that express LC markers: CD1a, Langerin, cutaneous lymphocyte-associated antigen, CC chemokine receptor 6, E-cadherin, and Birbeck granules. The resulting cells display phagocytic activity and chemotaxis to macrophage inflammatory protein-1alpha (MIP-1alpha). In response to CD40 ligand and tumor necrosis factor alpha, the cells acquire a mature phenotype of dendritic cells that is characterized by up-regulation of human leukocyte antigen (HLA)-ABC, HLA-DR, CD80, CD86, CD40, and CD54 and appearance of CD83. These cells in turn show chemotaxis toward MIP-1beta and elicit activation of CD8(+) T cells and T helper cell type 1 polarization of CD4(+) T cells. Thus, blood monocytes can give rise to LCs upon exposure to the skin cytokine environment consisting of Delta-1, GM-CSF, and TGF-beta1, which may be, in part, relevant to the development of human epidermal LCs. Our results extend the functional scope of Notch ligand delta-1 in human hematopoiesis.

IL-4 and IL-10 synergistically inhibit survival of human blood monocytes supported by GM-CSF.

Interleukin (IL)-4 and IL-10 have a wide variety of activities in the immune system. We re-evaluated the action of IL-4 and IL-10 on human blood monocytes, myeloid dendritic cell (DC1) precursors, using a serum-free culture system. Both IL-4 and IL-10 inhibited the survival of CD14+ monocytes supported by granulocyte-macrophage colony-stimulating factor in a dose-dependent manner. When IL-4 and IL-10 were combined, they had synergistic effects at low doses and induced a profound suppression of CD14+ monocyte survival. When the optimal timing was determined, the exposure to IL-4 and IL-10 for the initial 2 days was essential for suppression of survival of CD14+ monocytes. Annexin V/propidium iodide staining indicates that the suppression of CD14+ monocyte survival induced by IL-4 and IL-10 results from apoptosis. Tumor necrosis factor-alpha and lipopolysaccharide abrogated the effects of IL-4 and IL-10 on CD14+ monocytes, albeit incompletely. Thus, IL-4 in synergy with IL-10 negatively regulates the survival of DC1 precursor monocytes by inducing their apoptosis, which is modulated by factors such as tumor necrosis factor-alpha and lipopolysaccharide. Our data suggest the primary activities of IL-4 and IL-10 in DC1-mediated immune responses.