To identify risk variants for childhood acute lymphoblastic leukemia (ALL) we conducted a genome-wide association study of 2 case-control series, analyzing the genotypes of 291,423 tagging SNP genotypes in a total of 907 ALL cases and 2,398 controls. We identified risk loci for ALL at 7p12.2 (IKZF1, rs4132601; OR = 1.69, P = 1.20 x 10-19), 10q21.2 (ARIDB5, rs7089424; OR = 1.65, P = 6.69 x 10-19) and 14q11.2 (CEBPE, rs2239633; OR = 1.34, P = 2.88 x 10-7). The 10q21.2 (ARIDB5) risk association appears to be selective for the subset of B-cell precursor ALL with hyperdiploidy. These data show that common low-penetrance susceptibility alleles contribute to the risk of developing childhood ALL and provide novel insight into disease causation of this hematological cancer; notably all 3 risk variants map to genes involved in transcriptional regulation and differentiation of B-cell progenitors.

Objective. There is an increased interest in rheumatology in mesenchymal progenitor/stem cells (MPCs) and their roles in rheumatic diseases, but little is known about the phenotype of these cells in vivo. The aim of this study was to isolate and characterize human bone marrow (BM) MPCs.Methods. Fluorescence microscopy was used to identify putative MPCs among adherent BM cells. To purify them, a positive selection with antifibroblast microbeads was used, combined with fluorescenceactivated cell sorting (FACS) for microbead؉,CD45 low cells. A more detailed phenotype of these cells was determined using 4-color flow cytometry, and standard chondrogenic, osteogenic, and adipogenic assays were used to investigate their differentiation potentials.Results. Putative MPCs microscopically identified as large, fibroblast-like, D7-FIB؉ cells were purified using positive selection with D7-FIB-conjugated (antifibroblast) microbeads followed by FACS for specifically bound microbead؉,CD45 low cells. These cells represented 0.01% of mononuclear cells in the BM. They were uniformly positive for CD105, LNGFR, HLA-DR, CD10, CD13, CD90, STRO-1, and bone morphogenetic protein receptor type IA (BMPRIA) and were negative for CD14, CD34, CD117, and CD133. Only cells with this phenotype could proliferate and produce adherent cell monolayers capable of chondrogenic, osteogenic, and adipogenic differentiation. D7-FIB؊ cells in the BM lacked any MPC activity. Uncultured skin fibroblasts had a phenotype similar to that of BM MPCs, but were negative for LNGFR, STRO-1, HLA-DR, and BMPRIA.Conclusion. This study shows the distinct phenotype, morphology, and method of isolation of BM MPCs. The findings may have implications for defining the physiologic roles of MPCs in arthritis, bone diseases, and joint regeneration.

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor with a key role in several pathological processes, including tumour vascularization. Our preliminary observations indicated higher VEGF concentrations in serum samples than in matched plasma samples. We have now demonstrated that this difference is due to the presence of VEGF within platelets and its release upon their activation during coagulation. In eight healthy volunteers, serum VEGF concentrations ranged from 76 to 854 pg ml(-1) and were significantly higher (P < 0.01) than the matched citrated plasma VEGF concentrations, which ranged from < 9 to 42 pg ml(-1). Using platelet-rich plasma, mean (s.d.) platelet VEGF contents of 0.56 (0.36) pg of VEGF 10(-6) platelets were found. Immunocytochemistry demonstrated the cytoplasmic presence of VEGF within megakaryocytes and other cell types within the bone marrow. From examination of the effects of blood sample processing on circulating VEGF concentrations, it is apparent that for accurate measurements, citrated plasma processed within 1 h of venepuncture should be used. Serum is completely unsuitable. The presence of VEGF within platelets has implications for processes involving platelet and endothelial cell interactions. e.g. wound healing, and in tumour metastasis, when platelets adhering to circulating tumour cells may release VEGF at points of adhesion to endothelium, leading to hyperpermeability and extravasation of cells. Images Figure 4 Figure 3

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SummaryCorticosteroids are an essential component of treatment for acute lymphoblastic leukaemia (ALL). Prednisolone is the most commonly used steroid, particularly in the maintenance phase of therapy. There is increasing evidence that, even in equipotent dosage for glucocorticoid effect, dexamethasone has enhanced lymphoblast cytotoxicity and penetration of the central nervous system (CNS) compared with prednisolone. Substitution of dexamethasone for prednisolone in the treatment of ALL might, therefore, result in improved event-free and overall survival. Children with newly diagnosed ALL were randomly assigned to receive either dexamethasone or prednisolone in the induction, consolidation (all received dexamethasone in intensification) and continuation phases of treatment. Among 1603 eligible randomized patients, those receiving dexamethasone had half the risk of isolated CNS relapse (P ¼ 0AE0007). Event-free survival was significantly improved with dexamethasone (84AE2% vs. 75AE6% at 5 years; P ¼ 0AE01), with no evidence of differing effects in any subgroup of patients. The use of 6AE5 mg/m 2 dexamethasone throughout treatment for ALL led to a significant decrease in the risk of relapse for all risk-groups of patients and, despite the increased toxicity, should now be regarded as part of standard therapy for childhood ALL.

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Severe chronic neutropenia (SCN) is defined as an absolute neutrophil (ANC) of less than