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.

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.

Identification of signature genes by microarray for acute myeloid leukemia without maturation and acute promyelocytic leukemia with t(15;17)(q22;q12)(PML/RARalpha).

Acute myeloid leukemia (AML) has distinct subgroups characterized by different maturation and specific chromosomal translocation. In order to gain insight into the gene expression activities in AML, we carried out a gene expression profiling study with 21 AML samples using cDNA microarrays, focusing on acute promyelocytic leukemia with specific translocation t(15;17)(q22;q12) [French-American-British or FAB-M3 with t(15;17)] and AML without maturation (FAB-M1) characterized by morphologically and phenotypically immature AML blasts and no recurrent chromosomal abnormalities. Using a multivariate sigma-classifier algorithm, we identified 33 strong feature genes that distinguish FAB-M3 with t(15;17) from other AML samples, and 24 strong feature genes that classify FAB-M1. A direct comparison between FAB-M3 with t(15;17) and FAB-M1 led to selection of 13 strong feature genes. Those genes include some known to be related to leukemogenesis and cell differentiation. RIN1, a gene in the ras pathway, was up-regulated in FAB-M3 with t(15;17). Growth factor-binding protein 2 gene was down-regulated in FAB-M1. Huntingtin gene was up-regulated in FAB-M1. Others include syndecan 4, interleukin-2 receptor beta, folate receptor beta, low affinity immunoglobulin gamma, Fc receptor IIC precursor, insulin-like growth factor binding protein 2, and myeloperoxidase, which are involved in cell differentiation. Overexpression of myeloperoxidase in FAB-M3 cells with t(15;17) compared to FAB-M1 cells is consistent with the conventional cytochemical staining pattern. Thus, the study revealed that a morphologically-defined FAB-M1 subtype has a distinct gene expression signature that contributes to its cell differentiation and proliferation as well as FAB-M3 with a recurrent cytogenetic abnormality t(15;17)(q22;q12).