Reduced chondroitin sulfate content prevents diabetic neuropathy through transforming growth factor-ß signaling suppression.

Diabetic neuropathy (DN) is a major complication of diabetes mellitus. Chondroitin sulfate (CS) is one of the most important extracellular matrix components and is known to interact with various diffusible factors; however, its role in DN pathology has not been examined. Therefore, we generated CSGalNAc-T1 knockout (T1KO) mice, in which CS levels were reduced. We demonstrated that diabetic T1KO mice were much more resistant to DN than diabetic wild-type (WT) mice. We also found that interactions between pericytes and vascular endothelial cells were more stable in T1KO mice. Among the RNA-seq results, we focused on the transforming growth factor ß signaling pathway and found that the phosphorylation of Smad2/3 was less upregulated in T1KO mice than in WT mice under hyperglycemic conditions. Taken together, a reduction in CS level attenuates DN progression, indicating that CS is an important factor in DN pathogenesis.

Decade-long WT1-specific CTLs induced by WT1 peptide vaccination.

INTRODUCTION: The peptide-based cancer vaccine targeting Wilms' tumor 1 (WT1) is a promising immunotherapeutic strategy for hematological malignancies. It remains unclear how long and to what extent the WT1-specific CD8 + cytotoxic T cell (CTL) persist after WT1 peptide vaccination. METHODS: The WT1 peptide vaccine was administered with written consent to a patient with CML in the chronic phase who did not respond well to imatinib, and the patient was followed for 12 years after vaccination. Immune monitoring was performed by specific amplification of WT1-specific CTLs using a mixed lymphocyte peptide culture. T-cell receptors (TCRs) of amplified WT1-specific CTLs were analyzed using next-generation sequencing. This study was approved by the Institutional Review Board of our institution. RESULT: WT1-specific CTLs, which were initially detected during WT1 peptide vaccination, persisted at a frequency of less than 5 cells per 1,000,000 CD8 + T cells for more than 10 years. TCR repertoire analysis confirmed the diversity of WT1-specific CTLs 11 years after vaccination. CTLs exhibited WT1 peptide-specific cytotoxicity in vitro. CONCLUSION: The WT1 peptide vaccine induced an immune response that persists for more than 10 years, even after cessation of vaccination in the CML patient.

Genetic manipulation resulting in decreased donor chondroitin sulfate synthesis mitigates hepatic GVHD via suppression of T cell activity.

Donor T cell activation, proliferation, differentiation, and migration are the major steps involved in graft-versus-host disease (GVHD) development following bone marrow transplantation. Chondroitin sulfate (CS) proteoglycan is a major component of the extracellular matrix and causes immune modulation by interacting with cell growth factors and inducing cell adhesion. However, its precise effects on immune function are unclear than those of other proteoglycan families. Thus, we investigated the significance of CS within donor cells in acute GVHD development utilizing CSGalNAc T1-knockout (T1KO) mice. To determine the effects of T1KO, the mice underwent allogenic bone marrow transplantation from major histocompatibility complex-mismatched donors. While transplantation resulted in hepatic GVHD with inflammatory cell infiltration of both CD4+ and CD8+ effector memory T cells, transplantation in T1KO-donors showed milder cell infiltration and improved survival with fewer splenic effector T cells. In vitro T-cell analyses showed that the ratio of effector memory T cells was significantly lower via phorbol myristate acetate/ionomycin stimulation. Moreover, quantitative PCR analyses showed significantly less production of inflammatory cytokines, such as IFN-γ and CCL-2, in splenocytes of T1KO mice. These results suggest that reduction of CS in donor blood cells may suppress the severity of acute GVHD after hematopoietic stem cell transplantation.

Comparison of transplant outcomes between haploidentical transplantation and single cord blood transplantation in non-remission acute myeloid leukaemia: A nationwide retrospective study.

Allogeneic haematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for some patients with acute myeloid leukaemia (AML) who are refractory to chemotherapy. Cord blood transplantation (CBT) is a reasonable option in such cases because of its rapid availability. Recently, a growing number of human leucocyte antigen (HLA)-haploidentical related donor HSCTs (haplo-HSCTs) have been performed, although its effectiveness remains undetermined. Using the Japanese nationwide transplantation registry data, we identified 2438 patients aged ≥16 years who received CBT or haplo-HSCT as their first transplant for non-remission AML between January 2008 and December 2018. After 2:1 propensity score matching, 918 patients in the CBT group and 459 patients in the haplo-HSCT group were selected. In this matched cohort, no significant difference in overall survival (OS) was observed between the CBT and haplo-HSCT groups (hazard ratio [HR] of haplo-HSCT to CBT 1.02, 95% confidence interval [CI] 0.89-1.16). Similarly, no significant difference in the cumulative incidence of relapse (HR 1.09, 95% CI 0.93-1.28) or non-relapse mortality (HR 0.94, 95% CI 0.76-1.18). Subgroup analysis showed that CBT was significantly associated with preferable OS in patients receiving myeloablative conditioning. Our data showed comparable outcomes between haplo-HSCT and CBT recipients with non-remission AML.

Incidence and predictors of recurrent sick leave in survivors who returned to work after allogeneic hematopoietic cell transplantation.

BACKGROUND: Although rather favorable probabilities of return to work have been reported after allogeneic hematopoietic cell transplantation (allo-HCT), survivors often have difficulty continuing to work because of their immunocompromised status and diverse late effects after allo-HCT. We evaluated the incidence of and risk factors for recurrent sick leave in allo-HCT survivors after they initially returned to work. METHODS: We targeted allo-HCT survivors who were employed at diagnosis, aged 20-64 at survey, and survived for ≥ 2 years without relapse. Of the 1904 survivors who were informed of the study, 1148 returned the questionnaire (60%), and 1048 eligible participants were included in the overall analysis. In the present study that considered recurrent sick leave after return to work, we targeted 896 participants who returned to work at least once after allo-HCT. Participants stated if they had recurrent sick leave after returning to work and its reasons, as well as associated patient-, HCT/HCT center-, and work-related factors and clinical events after allo-HCT. A logistic regression analysis was conducted to explore correlated factors for recurrent sick leave. RESULTS: In survivors who returned to work, 30% required recurrent sick leave. The most frequent causes of recurrent leave were physical issues (72%), and analysis of free descriptions demonstrated that these were mainly associated with graft-versus-host disease, infection, or readmission. Other reasons included work-related issues such as gap between physical and working conditions. Multivariate analysis showed that cord blood transplantation, longer employment duration, and counseling from healthcare professionals were associated with a lower risk of recurrent leave. Readmission, immunosuppressant use, and symptoms involving the respiratory system, gut, and joints and muscles were associated with a higher risk. CONCLUSIONS: Our results drawn from a large cohort study should help healthcare professionals identify and assist at-risk patients. Multi-professional teams that provide continuous support and effective communication with the workplace are necessary to improve long-term outcomes after allo-HCT. IMPLICATIONS FOR CANCER SURVIVORS: In order to continue working after the initial return to work, it is important to receive counseling from healthcare professionals and obtain reasonable accommodation from workplace.

Comparable survival outcomes with haploidentical stem cell transplantation and unrelated bone marrow transplantation.

We retrospectively compared outcomes of unrelated donor bone marrow transplant (UBMT) and HLA-haploidentical peripheral blood stem cell transplantation using post-transplant cyclophosphamide (PTCy-haploPBSCT) using the Japanese registry data. Recipients of first HCT for acute leukemia and myelodysplastic syndromes between 2012 and 2015 were included. The analyzed subjects comprised UBMT recipients with 8/8 matched HLA alleles (n = 1470), 7/8 matched alleles (n = 859), 6/8 matched alleles (n = 186), and recipients of PTCy-haploPBSCT (n = 133). In multivariate analyses with 8/8 matched UBMT as the reference, PTCy-haploPBSCT showed similar overall mortality, decreased risk of non-relapse mortality (NRM), increased risk of relapse, and decreased risk of grade II-IV acute graft-versus-host disease (GVHD) and chronic GVHD. Adjusted probabilities for 8/8 matched UBMT, PTCy-haploPBSCT, and 7/8 and 6/8 matched UBMT groups at 2 years post-transplant were 61%, 60%, 58%, and 52% for overall survival, 23%, 28%, 21%, and 19% for relapse, and 20%, 7%, 24%, and 33% for NRM. PTCy-haploPBSCT was associated with remarkably low NRM, contributing to survival outcomes that were comparable to 8/8 matched UBMT. The higher relapse rate in the PTCy-haploPBSCT group might be associated with the higher proportion of high-risk patients. PTCy-haploPBSCT may be a viable alternative when HLA-matched related donors are not available.

Prognostic impact of complex karyotype on post-transplant outcomes of myelofibrosis.

Chromosomal abnormalities in the role of prognostic factor for transplant patients with myelofibrosis (MF) are not fully investigated. Regarding complex karyotype (CK), we retrospectively analyzed 241 patients with primary and secondary MF who received a first allogeneic hematopoietic cell transplantation (HCT). Based on an unfavorable karyotype in the Dynamic International Prognostic Scoring System, we compared the outcomes in 3 groups: favorable karyotype, unfavorable karyotype including CK (unfavorable-CK(+)), and unfavorable karyotype not including CK (unfavorable-CK(-)). Overall survival was significantly shorter in the unfavorable-CK(+) group (hazard ratio (HR) 2.49, 95% CI: 1.46-4.24, P < 0.001), whereas there was no difference between the unfavorable-CK(-) group and the favorable group (HR 0.57, 95% CI: 0.20-1.59, P = 0.28). In addition, a significantly higher proportion of patients in the unfavorable-CK(+) group did not achieve complete remission after HCT (P = 0.007). The cumulative incidence of disease progression was significantly higher in the unfavorable-CK(+) group (HR 2.5, 95% CI 1.6-3.92, P < 0.001), whereas that in the unfavorable-CK(-) group was comparable to that in the favorable group (HR 0.49, 95% CI 0.12-1.94, P = 0.31). Further investigations will be needed to clarify the impact of CK on transplant outcomes in MF.

Comparable survival outcomes with haploidentical stem cell transplantation and cord blood transplantation.

HLA-haploidentical stem cell transplantation using post-transplant cyclophosphamide (PTCy-haplo) and umbilical cord blood transplantation (UCBT) are alternative to HLA-matched stem cell transplantation. We conducted a matched-pair analysis of PTCy-haplo and UCBT using the Japanese registry data. We identified 136 patients aged between 16 and 69 years who received PTCy-haplo as their first transplantation for acute leukemia or myelodysplastic syndromes. Control group included 408 UCBT recipients selected to match the PTCy-haplo group. Overall and relapse-free survival probabilities at 2 years were comparable between the PTCy-haplo and UCBT groups: 55% vs. 53% for overall survival (p = 0.46), and 47% vs. 48% for relapse-free survival (p = 0.79), respectively. The cumulative incidence of relapse was significantly higher (43% vs. 29%, respectively, p = 0.006), while the cumulative incidence of non-relapse mortality (NRM) was significantly lower (9% vs. 23%, respectively, p < 0.001) in the PTCy-haplo group. The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) was lower in the PTCy-haplo group compared to the UCBT group (29% vs. 41%, respectively, p = 0.016), while those of grade III-IV acute GVHD and chronic GVHD were not statistically different between the two groups. Our results suggest that both PTCy-haplo and UCBT are viable alternatives to HLA-matched stem cell transplantation.

YAP1/TAZ activity maintains vascular integrity and organismal survival.

Radiation therapy is one of the major treatment modalities for patients with cancers. However, ionizing radiation (IR) damages not only cancer cells but also the surrounding vascular endothelial cells (ECs). Hippo pathway effector genes Yap1 and Taz are the two transcriptional coactivators that have crucial roles in tissue homeostasis and vascular integrity in various organs. However, their function in adult ECs at the steady state and after IR is poorly understood. Here, we report sex- and context-dependent roles of endothelial YAP1/TAZ in maintaining vascular integrity and organismal survival. EC-specific Yap1/Taz deletion compromised systemic vascular integrity, resulting in lethal circulation failure preferentially in male mice. Furthermore, EC-specific Yap1/Taz deletion induced acute lethality upon sublethal IR that was closely associated with exacerbated systemic vascular dysfunction and circulation failure. Consistent with these findings, RNA-seq analysis revealed downregulation of tight junction genes in Yap1/Taz-deleted ECs. Collectively, our findings highlight the importance of endothelial YAP1/TAZ for maintaining adult vascular function, which may provide clinical implications for preventing organ injury after radiation therapy.

Registry data analysis of hematopoietic stem cell transplantation on systemic chronic active Epstein-Barr virus infection patients in Japan.

The effects of allogeneic hematopoietic stem cell transplantation (allo-HSCT) on systemic chronic active Epstein-Barr virus infection (sCAEBV) are yet to be analyzed in a large number of patients. Using the Japanese registry database, Transplant Registry Unification Management Program, we investigated the outcomes of 102 sCAEBV patients who underwent allo-HSCT. The median age at HSCT was 21 years, and the three-year overall survival (3-year OS) rate was 72.5%. Of the 90 patients whose viral load after allo-HSCT was evaluated, 56 (62.2%) achieved a virological complete response, defined by the complete resolution of disease activity with a significant decrease in EBV-DNA in peripheral blood. The multivariate Cox proportional hazard model indicated that advanced age, in adolescents and young adults (AYA) (age, 15-39) and adults (age, ≥40 years) was a risk factor of poor OS. The hazard ratios (HRs) of the AYA and adult groups were 10.87 (95% confidence interval [CI]: 1.98-59.56, p = .006) and 15.93 (95% CI: 2.45-103.8, p = .004), respectively. Disease activity (HR 5.74), elevated soluble IL-2 receptor (sIL-2R) (≥ median, 691 U/mL) at HSCT (HR 6.93), and conditioning without radiotherapy (HR 3.53) were also independently associated with poor survival. Notably, 79% of radiotherapy doses were less than 6 Gy. Regardless of the presence of hemophagocytic lymphohistiocytosis, the group with a high sIL-2R level (≥2000 U/mL) showed a poorer prognosis. Although allo-HSCT is the only curative therapy for sCAEBV, treatment strategies need to be improved for high-risk patients, especially those with high levels of sIL-2R.

Intensive oral care can reduce bloodstream infection with coagulase-negative staphylococci after neutrophil engraftment in allogeneic hematopoietic stem-cell transplantation.

PURPOSE: Bloodstream infection (BSI) is a major complication of allogeneic hematopoietic stem-cell transplantation (allo-SCT). There are several causes of BSI; in particular, severe oral mucositis (OM) can induce BSI due to coagulase-negative staphylococci (CoNS). The OM severity may be reduced with intensive oral care. Thus, we evaluated whether the type of oral care affects the BSI incidence eventually. METHOD: We performed retrospective analysis on 206 recipients who underwent allo-SCT from 2006 to 2017 at our institute. Intensive oral care by a dental specialist was performed for 111 recipients (intensive-care group) and self-oral care was performed by 95 recipients (self-care group). Incidence of BSI was assessed by type of the oral care, before neutrophil engraftment (pre-E-BSI) and after neutrophil engraftment (post-E-BSI) period until 180 days after allo-SCT. RESULT: A total of 112 BSI occurred in 90 of the 206 recipients and 120 bacteria were identified, with CoNS being the most prevalent. There was no significant difference in the incidence of pre-E-BSI between the self-care and intensive-care groups (30.8% and 30.6%, respectively; P = 0.508). Meanwhile, the incidence of post-E-BSI was significantly lower in the intensive-care group than in the self-care group (14.3% and 28.6%; P = 0.008). In addition, the intensive-care group had significantly lower incidence of post-E-BSI with CoNS than the self-care group (8.5% and 21.5%, respectively; P = 0.009). CONCLUSION: Intensive oral care through the period of allo-HCT can significantly reduce the post-E-BSI occurrence, especially due to CoNS.

Altered microbiota by a high-fat diet accelerates lethal myeloid hematopoiesis associated with systemic SOCS3 deficiency.

The suppressors of cytokine signaling (SOCS) proteins are negative regulators of cytokine signaling required to prevent excessive cellular responses. In particular, SOCS3 is involved in the regulation of metabolic syndromes, such as obesity and diabetes, by suppressing leptin and insulin signals. SOCS3 also suppresses the inflammatory response associated with metabolic stress, but this specific role remains undefined. Wild-type mice on a high-fat diet (HFD) exhibited only fatty liver, whereas systemic deletion of SOCS3 resulted in excessive myeloid hematopoiesis and hepatic inflammation. In addition, depletion of the gut microbiota resulted in considerable improvement in excess granulopoiesis and splenomegaly, halting the progression of systemic inflammation in SOCS3KO mice on the HFD. This result suggests that intestinal dysbiosis is involved in inflammation associated with SOCS3KO. Although contributing to diet-induced obesity and fatty liver, SOCS3 is nevertheless critical to suppress excess myeloid hematopoiesis and severe systemic inflammation associated with intestinal dysbiosis on HFD.

Syngeneic hematopoietic stem cell transplantation for acute myeloid leukemia: a propensity score-matched analysis.

The present study evaluated outcomes and prognostic factors in adult patients with acute myeloid leukemia (AML) after syngeneic hematopoietic stem cell transplantation (HSCT). Among patients in first complete remission (CR1), outcomes of syngeneic HSCT (Syn) were compared with those of autologous HSCT (Auto), allogeneic HSCT from human leukocyte antigen (HLA)-matched sibling donor (MSD), or allogeneic HSCT from HLA-matched unrelated donor (MUD). Among 11,866 patients receiving first HSCT, 26 in the Syn group were analyzed. The 5-year overall survival (OS) rate, the cumulative incidence of relapse, and the cumulative incidence of non-relapse mortality (NRM) were 47.8%, 59.6%, and 4.6%, respectively. The OS was significantly better in patients in CR1 (n = 13) than in patients in non-CR1 (P = 0.012). Furthermore, 39 patients in CR1 each were assigned to the Auto, MSD, and MUD groups using propensity score matching. The 5-year OS in the Syn (68.4%) was not significantly different from those in the Auto (55.9%, P = 0.265), MSD (62.4%, P = 0.419), or MUD (63.7%, P = 0.409) groups. A higher relapse in the Syn than in the MSD and MUD groups was offset by lower NRM. In summary, syngeneic HSCT might be an alternative option for AML patients in CR1.

Prognostic value of measurable residual disease at allogeneic transplantation for adults with core binding factor acute myeloid leukemia in complete remission.

Pretransplant measurable residual disease (MRD) has been shown to be associated with relapse incidence following allogeneic hematopoietic cell transplantation (HCT) for acute myeloid leukemia (AML). However, it remains less clear whether pretransplant MRD status affects transplant outcomes in core binding factor AML (CBF-AML). We retrospectively evaluated the effect of pretransplant MRD, which was measured by a polymerase chain reaction of RUNX1-RUNX1T1 or CBFB-MYH11 fusion transcripts, on transplant outcomes for a cohort of 959 adult patients with t(8;21) or inv(16) AML treated by allogeneic HCT during complete remission (CR), between 2000 and 2018. Multivariate analysis showed the absence of pretransplant MRD was significantly associated with lower relapse (hazard ratio [HR], 0.46; P < 0.001), treatment failure (HR, 0.66; P = 0.004), and overall mortality (HR, 0.72; P = 0.037) among patients with t(8;21). However, pretransplant MRD negativity was not associated with relapse (HR, 0.73; P = 0.420), treatment failure (HR, 0.64; P = 0.063), or overall mortality (HR, 0.69; P = 0.149) among patients with inv(16). In subgroup analysis, pretransplant MRD status significantly affected relapse and LFS only in patients with t(8;21) undergoing allogeneic HCT during CR2. In conclusion, our data demonstrate the different prognostic values of pretransplant MRD for CBF-AML, highlighting the need to develop effective therapeutic strategies for such MRD-positive patients.

DA-EPOCH-R therapy for high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements in a patient with renal dysfunction.

High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, also known as double-hit lymphoma, has been reported as refractory to R-CHOP therapy and requires more intensive regimens. However, intensive and safe regimens for patients with renal dysfunction are unknown. Herein, we report the successful use of DA-EPOCH-R therapy for double-hit lymphoma in a 64-year-old man with renal dysfunction. The patient had lymphoma-induced bilateral ureteral obstruction. Although renal dysfunction remained after removing the obstruction using R-CHOP therapy, we completed six cycles of DA-EPOCH-R therapy without any major adverse events. DA-EPOCH-R therapy may be a safe regimen for renal dysfunction patients.

Single cord blood transplantation for acute myeloid leukemia patients aged 60 years or older: a retrospective study in Japan.

The availability of alternative donor sources could allow elderly patients to receive allogeneic hematopoietic cell transplantation (HCT). We retrospectively evaluated the outcomes of single-unit cord blood transplantation (CBT) in 1577 patients aged ≥60 years with acute myeloid leukemia (AML) in Japan between 2002 and 2017. In total, 990 (63%) patients were not in complete remission (CR) at the time of CBT. A myeloablative conditioning regimen (52%) and calcineurin inhibitor (CI) + mycophenolate mofetil (MMF)-based graft-versus-host disease (GVHD) prophylaxis (45%) were more commonly used. With a median follow-up for survivors of 31 months, the probability of overall survival and the cumulative incidence of leukemia-related mortality at 3 years was 31% and 29%, respectively. The cumulative incidence of non-relapse mortality (NRM) at 100 days and 3 years were 24% and 41%, respectively. The cumulative incidences of grade II-IV and grade III-IV acute GVHD at 100 days and extensive chronic GVHD at 2 years were 44%, 16%, and 14%, respectively. The cumulative incidence of neutrophil engraftment was 80% at 42 days. Results of multivariate analysis indicated that the following factors were significantly associated with higher overall mortality: performance status ≥1, hematopoietic cell transplantation-specific comorbidity index ≥3, adverse cytogenetics, extramedullary disease at diagnosis, and non-CR status at CBT. By contrast, female sex, HLA disparities ≥2, mycophenolate mofetil-based GVHD prophylaxis, and recent CBT were significantly associated with lower overall mortality. In conclusion, single CBT offers a curative option for AML patients aged ≥60 years with careful patient selection.

Distinct effects of chondroitin sulfate on hematopoietic cells and the stromal microenvironment in bone marrow hematopoiesis.

The bone marrow (BM) microenvironment, known as the BM niche, regulates hematopoiesis but is also affected by interactions with hematopoietic cells. Recent evidence indicates that extracellular matrix components are involved in these interactions. Chondroitin sulfate (CS), a glycosaminoglycan, is a major component of the extracellular matrix; however, it is not known whether CS has a physiological role in hematopoiesis. Here, we analyzed the functions of CS in hematopoietic and niche cells. CSGalNAcT1, which encodes CS N-acetylgalactosaminyltransferase-1 (T1), a key enzyme in CS biosynthesis, was highly expressed in hematopoietic stem and progenitor cells (HSPCs) and endothelial cells (ECs), but not in mesenchymal stromal cells (MSCs) in BM. In T1 knockout (T1KO) mice, a greater number of HSPCs existed compared with the wild-type (WT), but HSPCs from T1KO mice showed significantly impaired repopulation in WT recipient mice on serial transplantation. RNA sequence analysis revealed the activation of IFN-α/ß signaling and endoplasmic reticulum stress in T1KO HSPCs. In contrast, the number of WT HSPCs repopulated in T1KO recipient mice was larger than that in WT recipient mice after serial transplantation, indicating that the T1KO niche supports repopulation of HSPCs better than the WT niche. There was no obvious difference in the distribution of vasculature and MSCs between WT and T1KO BM, suggesting that CS loss alters vascular niche functions without affecting its structure. Our results revealed distinct roles of CS in hematopoietic cells and BM niche, indicating that crosstalk between these components is important to maintain homeostasis in BM.

WT1-specific CD8 + cytotoxic T cells with the capacity for antigen-specific expansion accumulate in the bone marrow in MDS.

Wilms' tumor 1 (WT1) is a tumor-associated antigen and immunotherapy target in myelodysplastic syndrome (MDS). Further information is needed on the characteristics of WT1-specific CD8 + T cells to develop immunotherapeutic strategies for MDS. To clarify the frequency, distribution, and phenotype of WT1-specific CD8 + T cells, which occur innately in MDS patients, we analyzed paired peripheral blood (PB) and bone marrow (BM) samples from 39 patients with MDS or acute myeloid leukemia with myelodysplasia-related changes. The median frequency of WT1 tetramer-binding CD8 + T cells in the CD8 + T cell population was 0.11% in PB and 0.18% in BM. A further tetramer assay combined with mixed lymphocyte peptide culture (MLPC assay) was used to detect functional WT1-specific CD8 + T cells that could respond to the WT1 peptide. Functional WT1-specific CD8 + T cells were detected in BM in 61% of patients, which was significantly higher than in PB (23%, p = 0.001). The frequency of these cells estimated by the MLPC assay was tenfold higher in BM than in PB. The majority of WT1 tetramer-binding CD8 + T cells in BM had a unique phenotype with co-expression of CD39 and CXCR4. These findings will facilitate the development of novel immunotherapeutic strategies for MDS.