Rapid immune recovery following allogeneic hematopoietic stem cell transplantation (allo-HSCT) is important for clinical outcome prediction. In most studies, immune recovery after allo-HSCT is monitored via peripheral blood. However, few reports regarding the status of absolute lymphocyte subsets in the bone marrow (BM) microenvironment have been undertaken. Therefore, we evaluated the clinical impact of immune recovery in the early period following allo-HSCT using BM samples. We showed that delayed natural killer cell recovery was independently associated with a poor prognosis for overall survival (hazard ratio [HR], 3.07; 95% confidence interval [CI], 1.37- 6.89; P = .007), progression-free survival (HR, 3.42; 95% CI, 1.47-7.94; P = .004), and nonrelapse mortality (HR, 6.68; 95% CI, 1.82-25.0; P = .004) by multivariate analysis. In addition, low NK cell counts were associated with the presence of 1 or more bacterial, viral, or fungal infections. Our results indicate that investigating absolute lymphocyte subsets in BM in the early phase following allo-HSCT can be useful for predicting and improving survival outcomes.

After allogeneic stem cell transplantation (alloSCT), several immune checkpoints play an important role in the antileukemic immune response in the bone marrow (BM) microenvironment. However, immune checkpoint expression levels in the BM have not been reported after alloSCT in patients with acute myeloid leukemia (AML). We investigated the clinical impact of immune checkpoint expression in BM samples after alloSCT for AML. Higher expression of T cell immunoreceptor with Ig and ITIM domains (TIGIT) was associated with a decreased incidence of acute graft-versus-host disease (P = .048) and poor overall (P = .046) and progression-free survival (P = 0.024). In addition, higher expression of TIGIT at engraftment after alloSCT was correlated with a decreased number of natural killer cells in BM (P = .019). Monitoring TIGIT expression in the BM could be useful for predicting outcome after alloSCT for AML. Our findings raise the possibility that blockade of TIGIT would improve survival.

Studies showed red cell distribution width (RDW) can improve the detection of morphological changes in red blood cells and the understanding of their contribution to dyserythropoiesis in myelodysplastic syndrome (MDS). The purpose of the study was to evaluate dyserythropoiesis in MDS by RDW analysis and to explore the utility of RDW in clinical practice. We retrospectively analyzed laboratory and clinical data of 101 patients (59 patients was refractory anemia (RA) according to the French-American-British (FAB) classification). In patients with RA, RDW was showed weak inverse correlation with both hemoglobin concentration (Hb) (r = -0.37, P = 0.0035) and mean corpuscular hemoglobin concentration (MCHC) (r = -0.36, P = 0.0047). On the other hand, RDW was showed weak correlation with the number of ringed sideroblasts in bone marrow (r = 0.31, P = 0.023). The increased RDW (≥15.0%) was associated with shorter overall survival (OS) (P = 0.0086). In patients with refractory anemia with excess blasts (RAEB) and RAEB in transformation (RAEB-t), effect of RDW on OS was less evident. These results suggested that increased RDW might reflect dyserythropoiesis, associated with deregulated hemoglobin synthesis and iron metabolism in MDS. Furthermore, increased RDW may have potential to be a prognostic significance in RA.

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Rituximab, anti-CD20 monoclonal antibody, shows anti-lymphoma effects by either activating host immune mechanism against lymphoma cells such as ADCC and CDC or suppressing signal(s) important for growth of B-cell lymphoma. Accumulated evidence shows de-regulated PI3K-AKT pathway is important therapeutic target in B-cell lymphoma. Although studies suggested suppression of PI3K-AKT pathway is possibly critical in rituximab-induced anti-lymphoma signals, details of molecular mechanisms covering CD20-mediated signals and PI3K-AKT pathway are still unknown. We analyzed signals in B-cell lymphoma cell line, SD07, which had bi-allelic deletions of both CD20(MS4A1) and PTEN gene. Briefly, SD07 was established from a patient with diffuse large B-cell lymphoma(DLBCL)who showed refractory CD20-negative relapse(Eur.J. Haematol. 2012). We transiently restored protein expression of either or both of CD20 and PTEN by electroporation of expression plasmid having cDNA of those genes in SD07. In this experiment, expression of both proteins were clearly detected by western blot until 72 hours after transfection. CD20 protein was also detectable on cell surface of SD07 cells by flow cytometric(FCM) analysis at comparable levels of those of Daudi cells after transfection on CD20 cDNA. Our previous study showed expression of both c-myc RNA and protein, as judged by FCM, was induced by transient transfection of CD20 cDNA in SD07 cells. Western blot analysis also showed significant increase of myc protein 24hrs after transfection (vector=13.7±0.2, CD20=14.5±0.4, P<0.05, arbitrary density unit) and the increase was not affected by the addition of rituximab(20µg/ml)in culture. In contrast transfection of PTEN cDNA produced significant decrease of myc protein (PTEN=11.2±0.1, P<0.01). Myc protein levels was comparable between cells transfected with CD20 plus PTEN and PTEN alone. However in the presence of rituximab, myc protein expression was markedly downregulated in SD07 cells at both 24 hours(vector=13.7±0.2,CD20+PTEN=8.3±0.1,P=0.0008)and 48hours(vector=12.4±0.3 vs CD20+PTEN=11.2±0.1,P=0.04). 24 hours after transfection, de-phosphorylation and down-regulation of retinoblastoma(RB) protein expression was evident only in SD07 cells transfected with both CD20 and PTEN, but not with either alone. Rituximab also augmented down-regulation of RB protein in SD07 cells transfected with both CD20 and PTEN. After transfection, in vitro cell growth of SD07, as evaluated by MTT, was as follows;vector=4.6±0.3, CD20=4.8±0.3(P=NS), PTEN=4.1±0.2(P<0.05), CD20+PTEN=3.6±0.2(P<0.01), CD20+PTEN+rituximab=2.7±0.2(P<0.01),OD570nm, days3) 72 hours after transfection, by FCM, SD07 transfected with both CD20 and PTEN showed significant increase of subG1 DNA content potion compared with cells transfected with either alone(vector=2.5±0.2%,CD20=5.3±0.2%,PTEN=8.8 ±0.5%,CD20+PTEN= 16.1±0.6, P<0.01). Furthermore, addition of rituximab significantly increase of cells in subG1 in SD07 with transfected with both CD20 and PTEN(18.6±0.5%,P<0.01), suggesting suppression of PI3K-AKT is important for mediateing rituximab-induced apoptotis. Accordance with proliferative effect of CD20 in SD07, transfection of CD20 alone produced significant increase of phosphorylation of AktSer473(vector=11.2±2.3, CD20=13.3±2.3,pAkt/total Akt,P<0.05). Co-transfection of PTEN with CD20 suppress the CD20-induced phosphorylation of Akt in SD07 cells. (CD20+PTEN=12.8±2.3,P=NS). In summary, although data is limited in a cell line, it clearly shows rituximab-induced CD20-mediated signals and suppression of PI3K-AKT pathway by tumor suppressor PTEN cooperatively inhibits growth and induce apoptosis of DLBCL cell line, SD07. Myc protein is critical molecules in this particular cooperative pathways. The present result partly agree studies which showed that inhibition of PI3K-AKT signaling and down-regulation of myc is important in PTEN-induced cytotoxicity in GCB(germinal center B cell)type DLBCL. In addition, we show here myc is not only for PTEN, but also involved in rituximab-induced anti-lymphoma effect. The present result provide a rationale for combination of rituximab and PI3K inhibitor in the treatment of DLBCL. In this context, myc is a candidate of the therapeutic target in rituximab-based immunochemotherapy for B cell lymphoma. Disclosures No relevant conflicts of interest to declare.

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