IntroductionB-cell malignancies of children and adults, such as acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphoma (NHL), are often incurable even with intensive chemotherapy. For many patients, bone marrow ablation followed by allogeneic hematopoietic stem cell transplantation is the only potentially curative option, but the disease may return after transplantation. 1 The well-documented association between T-cellmediated graft-versus-host disease (GvHD) and a delay or suppression of leukemic relapse after allogeneic stem cell transplantation 2-4 has led some investigators to manipulate GvHD by infusion of donor T lymphocytes. Although this procedure can induce a measurable antineoplastic response, [5][6][7][8] it carries the risk of severe GvHD, particularly in those patients (Ͼ 70%) who lack an HLA-identical donor. Moreover, in some B-cell malignancies, such as ALL, the effect of lymphocyte infusions is often inadequate. 6,9,10 Besides T lymphocytes, natural killer (NK) cells also exert cytotoxicity against cancer cells. 11 Recent studies have emphasized the potential of NK-cell therapy in recipients of allogeneic hematopoietic stem cell transplants. In animal models of transplantation, donor NK cells could lyse leukemic cells and host lymphohematopoietic cells without affecting nonhematopoietic tissues, 12 suggesting that NK-mediated graft-versus-leukemia responses may occur in the absence of systemic disease. Because NK cells are inhibited by self-HLA molecules, which bind to killer immunoglobulin-like receptors (KIRs), these findings have led to the clinical practice of selecting hematopoietic stem cell transplantation donors with an HLA and KIR type that favors NK-cell activation and thus could be expected to promote an antileukemic effect. [13][14][15] However, selection of the "best" donor is limited to patients who have more than one potential donor and the capacity of NK cells to lyse lymphoid cells is generally low and difficult to predict. 13,[15][16][17] Emerging evidence indicates that T lymphocytes genetically modified with chimeric receptors able to recognize a surface molecule of target cells and transduce activation signals can specifically enhance T-cell cytotoxicity against cancer cells both in vitro and in vivo. [18][19][20][21] The studies presented here are based on the concept that expression of chimeric receptors on NK cells could overcome HLA-mediated inhibitory signals, thus endowing the cells with cytotoxicity against otherwise NK-resistant cells. To test this hypothesis, we first developed a novel method that allows specific and vigorous expansion of NK cells lacking T-cell receptors (CD56 ϩ CD3 Ϫ cells) and their highly efficient transduction with chimeric receptors. Then, we tested the relative antileukemic effects of genetically modified NK cells bearing chimeric receptors (directed against CD19, a molecule widely expressed by malignant B cells) that deliver different primary and costimulatory signals. Materials and methods CellsThe C...

No abstract

Twenty percent to 30% of transient abnormal myelopoiesis (TAM) observed in newborns with Down syndrome (DS) develop myeloid leukemia of DS (ML-DS).Most cases of TAM carry somatic GATA1 mutations resulting in the exclusive expression of a truncated protein (GATA1s). However, there are no reports on the expression levels of GATA1s in TAM blasts, and the risk factors for the progression to ML-DS are unidentified. To test whether the spectrum of transcripts derived from the mutant GATA1 genes affects the expression levels, we classified the mutations according to the types of transcripts, and investigated the modalities of expression by in vitro transfection experiments using GATA1 expression constructs harboring mutations. We show here that the mutations affected the amount of mutant protein. Based on our estimates of GATA1s protein expression, the mutations were classified into GATA1s high and low groups. Phenotypic analyses of 66 TAM patients with GATA1 mutations revealed that GATA1s low mutations were significantly associated with a risk of progression to ML-DS (P < .001) and lower white blood cell counts (P ‫؍‬ .004). Our study indicates that quantitative differences in mutant protein levels have significant effects on the phenotype of TAM and warrants further investigation in a prospective study.

In childhood acute lymphoblastic leukemia (ALL), early response to treatment is a powerful prognostic indicator. To identify genes associated with this response, we analyzed gene expression of diagnostic lymphoblasts from 189 children with ALL and compared the findings with minimal residual disease (MRD) levels on days 19 and 46 of remission induction treatment. After excluding genes associated with genetic subgroups, we identified 17 genes that were significantly associated with MRD. The caspase 8-associated protein 2 (CASP8AP2) gene was studied further because of its reported role in apoptosis and glucocorticoid signaling. In a separate cohort of 99 patients not included in the comparison of gene expression profiles and MRD, low levels of CASP8AP2 expression predicted a lower event-free survival (P ‫؍‬ .02) and a higher rate of leukemia relapse (P ‫؍‬ .01) and were an independent predictor of outcome. High levels of CASP8AP2 expression were associated with a greater propensity of leukemic lymphoblasts to undergo apoptosis. We conclude that measurement of CASP8AP2 expression at diagnosis offers a means to identify patients whose leukemic cells are highly susceptible to chemotherapy. Therefore, this gene is a strong candidate for inclusion in gene expression arrays specifically designed for leukemia diagnosis.

Individualized intervention guided by BCR-ABL transcript levels after HLA-identical sibling donor transplantation improves HSCT outcomes for subjects with chronic myeloid leukemia.

Dendritic cell (DC) is the most potent activator of CD4+ T cells and has unique dendrites and veils. To explore the function of Rho in DC, exoenzyme C3 from Clostridium botulinum was used as a specific inhibitor of Rho. Treatment of DC with C3 (DC/C3) resulted in profound morphological changes by losing dendrites and emerging of shrunk membrane processes that were in parallel with marked reduction of polymerized actin in the marginal area. Inactivation of Rho-associated coiled coil-containing kinase (p160ROCK) by a specific ROCK inhibitor Y-27632 also led to disappearance of dendrites of DC with retaining large membrane expansions. In scanning electron microscopy, untreated DCs interacted with CD4+ T cells more efficiently than DC/C3. Conjugate formation assay showed that the number of DCs associated with CD4+ T cells was 2-fold higher in untreated DCs than that of DC/C3. Alloantigen-presenting capacity of DC/C3 was significantly suppressed in a dose-dependent manner. Because C3 treatment did not affect the surface expression of HLA, costimulatory, and adhesion molecules of DC, we examined cytokine production of DC and naive CD4+ T cells to further elucidate the inhibitory mechanism of MLR. Unexpectedly, DC/C3 increased IL-12 production after LPS stimulation. Naive CD4+ T cells cocultured with DC/C3 produced the increased percentage of IFN-γ-producing cells, whereas the percentage of IL-2-producing T cells was decreased. These results demonstrate that Rho GTPase in DC controls both characteristic shape and immunogenic capacity.

G-protein-coupled receptors (GPCRs) transduce the signal of a wide variety of chemokines, cytokines, neurotransmitters, hormones, odorants, and others to regulate the biologic homeostasis, including hematopoiesis and immunity. Here we report the molecular cloning of leukocytespecific STAT-induced GPCR (LSSIG), which is a novel murine orphan GPCR with the highest homology to human GPR43. The mRNA expression of LSSIG was clearly induced in M1 leukemia cells during the leukemia inhibitory factor (LIF)-induced differentiation to macrophages, and the induction was evidently signal transducers and activators of transcription 3 (STAT3)-dependent. GPR43 expression was also strongly induced in HL-60 and U937 leukemia cells during the differentiation to monocytes. Further analysis showed that the expression of both LSSIG and GPR43 is highly restricted in hematopoietic tissues. Cytokine-stimulation induced LSSIG and GPR43 in bone marrow cells, and monocytes and neutrophils, respectively. These results suggest that LSSIG and GPR43 might play pivotal roles in differentiation and immune response of monocytes and granulocytes. (Blood.

Infants (<1 year old) with acute myeloid leukemia (AML) are particularly vulnerable to intensive cytotoxic therapy. Indeed, the mortality rate was high among infants enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study, which prompted us to temporarily suspend patient enrollment and amend the protocol. Forty-five infants with AML were enrolled. For patients aged <2 years, drug doses were adjusted for body weight. Following the protocol amendments, doses for infants were reduced by a further 33 % in the initial induction course. Six infants died during the induction phase (including five early deaths), mainly due to pulmonary complications. The 3-year probability of overall survival (pOS) in all 45 infants [55.9 %, 95 % confidence interval (CI) 37.9-70.6 %] was significantly lower than that of patients aged 1 to <2 years (77.0 %, 95 % CI 62.7-86.3 %) and those aged ≥2 years (74.7 %, 95 % CI 69.2-79.4 %) (P = 0.037), mainly due to the higher non-relapse mortality rate in infants. No early deaths occurred after the protocol amendments, and the 3-year pOS of the 17 infants enrolled thereafter was 76.4 % (95 % CI 48.8-90.4 %). In conclusion, appropriate dose reduction is essential to avoid early deaths when treating infants with AML.