TRAF6 signaling in T cells is crucial for the pathogenicity of experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is an incurable chronic autoimmune disease affecting the central nervous system (CNS). Although IL-17-producing helper T (Th17) cells are thought to be one of the exacerbating factors in MS, the underlying pathogenic mechanism is incompletely understood. TNF receptor-associated factor 6 (TRAF6) deficient T cells exhibited enhanced Th17 cell differentiation, however, the physiological relevance of TRAF6 in T cells remains unknown. Here, we induced experimental autoimmune encephalomyelitis (EAE) in T cell-specific TRAF6 deficient (TRAF6ΔT) mice to investigate the role of TRAF6 in T cells during the course of MS using an EAE model. Although Th17 cell differentiation was enhanced in TRAF6ΔT mice, mutant mice were resistant to EAE. In contrast, TRAF6 loss did not affect regulatory T-cell differentiation. Consistent with the severity of EAE, a small number of infiltrating T cells and a small area of demyelination were observed in the CNS of TRAF6ΔT mice. Moreover, myelin oligodendrocyte glycoprotein-induced IL-17 production in TRAF6-deficient T cells was significantly suppressed. We further confirmed lower levels of CD69 and granulocyte-macrophage colony-stimulating factor in Th17 cells of TRAF6ΔT mice than in wild-type mice. In contrast, the expression of IL-10 and cytotoxic T-lymphocyte-associated protein 4 in T cells was significantly elevated in the absence of TRAF6 because of enhanced T-cell receptor signaling. Collectively, TRAF6 signaling in T cells contributes to the pathogenesis of EAE by regulating the pathogenicity and autoantigen reactivity of Th17 cells.

GM-CSF-producing CCR2+ CCR6+ Th17 cells are pathogenic in dextran sodium sulfate-induced colitis model in mice.

Although excessive immune responses by Th17 cells, a helper T cell subset, are implicated in the pathogenesis of inflammatory bowel disease (IBD), the mechanism by which its localization in an inflamed colon is regulated remains unclear. Chemokines and their receptors are involved in the pathogenesis of IBD, however, the relative significance of each receptor on Th17 cells remains unknown. We generated C-C motif chemokine receptor 2 (CCR2) knockout (KO) and CCR6 KO mice in the syngeneic background using the CRISPR/Cas9 system and found that the phenotypes of experimental colitis worsened in both mutant mice. Surprisingly, the phenotype of colitis in CCR2/CCR6-double knockout (CCR2/6 DKO) mice was opposite to that of the single-deficient mice, with significantly milder experimental colitis (p < .05). The same was true for the symptoms in CCR6 KO mice, but not in wild type mice treated with a CCR2 inhibitor, propagermanium. Colonic CCR2+ CCR6+ Th17 cells produced a potentially pathogenic cytokine GM-CSF whose levels in the gut were significantly reduced in CCR2/6 DKO mice (p < .05). These results suggest that GM-CSF-producing CCR2+ CCR6+ Th17 cells are pathogenic and are attracted to the inflamed colon by either CCR2 or CCR6 gradient, which subsequently exacerbates experimental colitis in mice.

CCL20/CCR6 chemokine signaling is not essential for pathogenesis in an experimental autoimmune encephalomyelitis mouse model of multiple sclerosis.

Multiple sclerosis is an autoimmune disease in which the immune system attacks the nerve myelin sheath. The balance between pathogenic Th17 cells and regulatory Treg cells, both of which express the chemokine receptor CCR6 is critical for determining disease activity. It has been postulated that CCL20, the cognate ligand of CCR6, produced by the blood-brain barrier attracts these immune cells to the central nervous system (CNS). However, the pathological phenotypes of the experimental model of multiple sclerosis in CCR6-knockout (KO) mice are inconclusive, while this has not been addressed in CCL20-KO mice. To address this, we generated CCL20-KO and CCR6-KO mice using the CRISPR/Cas9 system. Clinical phenotypes of experimental autoimmune encephalomyelitis (EAE) in the chronic phase were slightly exacerbated in both mutant mice relative to those in wild-type (WT) mice. Inflammatory cell infiltration and demyelination in the CNS were similar in the KO and WT mice. CNS CD4+ T cell counts were the same for mutant and WT mice. The mutant and WT mice did not differ significantly in the proportions of Th17 and Treg cells in the CNS, or in IL-17 and TGF-ß mRNA expression in the CNS. These findings suggest that CCL20/CCR6-mediated cell migration is not necessarily required for the onset of EAE, and may be compensated for by other chemokine signals.

TRAF6 signaling in dendritic cells plays protective role against infectious colitis by limiting C. rodentium infection through the induction of Th1 and Th17 responses.

Tumor necrosis factor receptor-associated factor 6 (TRAF6) plays a pivotal role in the induction of inflammatory responses not only in innate immune cells but also in non-immune cells, leading to the activation of adaptive immunity. Signal transduction mediated by TRAF6, along with its upstream molecule MyD88 in intestinal epithelial cells (IECs) is crucial for the maintenance of mucosal homeostasis following inflammatory insult. The IEC-specific TRAF6-deficient (TRAF6ΔIEC) and MyD88-deficient (MyD88ΔIEC) mice exhibit increased susceptibility to DSS-induced colitis, emphasizing the critical role of this pathway. Moreover, MyD88 also plays a protective role in Citrobacter rodentium (C. rodentium) infection-induced colitis. However, its pathological role of TRAF6 in infectious colitis remains unclear. To investigate the site-specific roles of TRAF6 in response to enteric bacterial pathogens, we infected TRAF6ΔIEC and dendritic cell (DC)-specific TRAF6-deficient (TRAF6ΔDC) mice with C. rodentium and found that the pathology of infectious colitis was exacerbated with significantly decreased survival rates in TRAF6ΔDC mice, but not in TRAF6ΔIEC mice, compared to those in control mice. TRAF6ΔDC mice showed increased bacterial burdens, marked disruption of epithelial and mucosal structures with increased infiltration of neutrophils and macrophages, and elevated cytokine levels in the colon at the late stages of infection. The frequencies of IFN-γ producing Th1 cells and IL-17A producing Th17 cells in the colonic lamina propria were significantly reduced in TRAF6ΔDC mice. Finally, we demonstrated that TRAF6-deficient DCs failed to produce IL-12 and IL-23 in response to C. rodentium stimulation, and to induce both Th1 and Th17 cells in vitro. Thus, TRAF6 signaling in DCs, but not in IECs, protects against colitis induced by C. rodentium infection by producing IL-12 and IL-23 that induce Th1 and Th17 responses in the gut.

Comprehensive lipidomics of lupus-prone mice using LC-MS/MS identifies the reduction of palmitoylethanolamide that suppresses TLR9-mediated inflammation.

Lipid mediators are known to play crucial roles not only in the onset of the inflammatory response but also in the induction of resolution of inflammation. Here, we report that palmitoylethanolamide (PEA), an endogenous N-acylethanolamine, can suppress the inflammation induced by Toll-like receptor (TLR) signaling both in vitro and in vivo. PEA was found to be significantly reduced in the serum and spleen of lupus-prone MRL/lpr mice analyzed by lipidomics. PEA suppressed pro-inflammatory cytokine production in a mouse macrophage cell line stimulated with TLR ligands such as lipopolysaccharide, peptidoglycan, poly (I:C), imiquimod, and CpG-ODN. PEA also inhibited both mRNA and protein levels of IL-6 in bone marrow-derived dendritic cells (BMDCs) and B cells stimulated with CpG-ODN. Augmentation of cell surface CD86 and CD40 on BMDCs and B cells, IgM production, and cell proliferation of B cells in response to CpG-ODN were attenuated by PEA. Moreover, PEA treatment significantly reduced mortality and serum IL-6 levels in mice injected with CpG-ODN plus D-galactosamine. Taken together, PEA ameliorates inflammation induced by TLR signaling, which could be a novel therapeutic target for inflammatory disorders.

TRAF6 signaling pathway in T cells regulates anti-tumor immunity through the activation of tumor specific Th9 cells and CTLs.

CD8+ cytotoxic T lymphocytes (CTLs) and CD4+ helper T (Th) cells play a critical role in protective immune responses to tumor cells. Particularly, Th9 cells exert anti-tumor activity by producing IL-9. TNF receptor (TNFR)-associated factor 6 (TRAF6) is an adaptor protein that mediates the signals from both the TNFR superfamily and Toll-like receptors (TLRs). We have previously reported that T cell-specific TRAF6-deficent (TRAF6ΔT) mice spontaneously developed systemic inflammatory diseases. However, the physiological role of TRAF6 in T cells in controlling anti-tumor immune responses remains largely unclear. Here, we found that tumor formation of syngeneic colon cancer cells inoculated in TRAF6ΔT mice was accelerated compared to that in control mice. Although TRAF6-deficient naïve T cells showed enhanced differentiation of Th9 cells in vitro, these T cells produced lower amounts of IL-9 in response to a specific antigen. Moreover, CD4+ tumor-infiltrating lymphocytes (TILs) in tumor-bearing TRAF6ΔT mice expressed lower levels of IL-9 than those in WT mice. Importantly, administration of recombinant IL-9 (rIL-9) strongly suppressed tumor progression in TRAF6ΔT mice. Furthermore, expression levels of the T-box transcription factor Eomesodermin (Eomes) and its target molecules IFN-γ, granzyme B and perforin, as well as cytotoxic activity, were reduced in TRAF6-deficient CD8+ T cells in vitro. TRAF6-deficient T cells were found to express significantly increased levels of immune checkpoint molecules, CTLA-4 and PD-1 on the cell surface. These results demonstrate that the TRAF6 signaling pathway in T cells regulates anti-tumor immunity through the activation of tumor specific Th9 cells and CTLs in a tumor microenvironment.

Protease inhibitory activity of secretory leukocyte protease inhibitor ameliorates murine experimental colitis by protecting the intestinal epithelial barrier.

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder in the intestine, and the dysfunction of intestinal epithelial barrier (IEB) may trigger the onset of IBD. Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that has been implicated in the tissue-protective effect in the skin and lung. We found that SLPI was induced in lipopolysaccharides-treated colon carcinoma cell line and in the colon of dextran sulfate sodium (DSS)-treated mice. SLPI-deficient mice were administered DSS to induce colitis and sustained severe inflammation compared with wild-type mice. The colonic mucosa of SLPI-deficient mice showed more severe inflammation with neutrophil infiltration and higher levels of proinflammatory cytokines compared with control mice. Moreover, neutrophil elastase (NE) activity in SLPI-deficient mice was increased and IEB function was severely impaired in the colon, accompanied with the increased number of apoptotic cells. Importantly, we demonstrated that DSS-induced colitis was ameliorated by administration of protease inhibitor SSR69071 and recombinant SLPI. These results suggest that the protease inhibitory activity of SLPI protects from colitis by preventing IEB dysfunction caused by excessive NE activity, which provides insight into the novel function of SLPI in the regulation of gut homeostasis and therapeutic approaches for IBD.

Development of a portable reverse transcription loop-mediated isothermal amplification system to detect the E1 region of Chikungunya virus in a cost-effective manner.

Chikungunya fever is a mosquito-borne disease cause of persistent arthralgia. The current diagnosis of Chikungunya virus (CHIKV) relies on a conventional reverse transcription polymerase chain reaction assay. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) is a rapid and simple tool used for DNA-based diagnosis of a variety of infectious diseases. In this study, we established an RT-LAMP system to recognize CHIKV by targeting the envelope protein 1 (E1) gene that could also detect CHIKV at a concentration of 8 PFU without incorrectly detecting other mosquito-borne viruses. The system also amplified the E1 genome in the serum of CHIKV-infected mice with high sensitivity and specificity. Moreover, we established a dry RT-LAMP system that can be transported without a cold chain, which detected the virus genome in CHIKV-infected patient samples with high accuracy. Thus, the dry RT-LAMP system has great potential to be applied as a novel CHIKV screening kit in endemic areas.

Association between Platelet-Associated Immunoglobulin G Levels and Response to Corticosteroid Therapy in Patients with Newly Diagnosed Immune Thrombocytopenia.

OBJECTIVE: Platelet-associated immunoglobulin G (PA-IgG) refers to IgG attached to the surface of platelets, while the immature platelet fraction (IPF) reflects the state of platelet production in bone marrow. Since PA-IgG and IPF are increased in patients with immune thrombocytopenia (ITP), reflecting amounts of platelet antibodies and compensatory platelet production, respectively, we hypothesized that these laboratory findings may provide useful markers for predicting treatment response in patients with ITP. We therefore retrospectively investigated associations between levels of these markers at diagnosis and response to first-line therapy in patients with ITP. METHODS: Forty-three patients diagnosed with ITP at Oita Kouseiren Tsurumi Hospital between May 2010 and November 2018 were included. Patients were divided into 2 groups based on response to corticosteroid as first-line therapy. Laboratory findings were compared between responders and nonresponders. RESULTS: Median PA-IgG was 285 ng/107 cells (range, 45.5-18,200 ng/107 cells), and median IPF was 15.5% (range, 5.4-62.1%). Median levels were higher than the respective upper limits of normal range (PA-IgG, 0-46 ng/107 cells; IPF, 1.1-9.5%). First-line therapy was performed using standard-dose prednisolone (0.5-1.0 mg/kg/day) in 32 patients and high-dose dexamethasone (40 mg/day, 4 days) or methylprednisolone (125-1,000 mg/day, 3-4 days) in 11 patients. Twenty-four patients (55.8%) responded to first-line therapy. In univariate analysis, type of corticosteroid (p = 0.17) tended to differ between groups but did not differ significantly, and no difference in IPF level was apparent between responders (15.35%; range, 5.4-41.5%) and nonresponders (16.7%; range, 6.3-62.1%; p = 0.15). PA-IgG was significantly higher among nonresponders (430 ng/107 cells; range, 101-18,200 ng/107 cells) than among responders (254.5 ng/107 cells; range, 45.5-470 ng/107 cells; p = 0.004). Multivariate analysis revealed PA-IgG was independently associated with response to first-line therapy (odds ratio, 1.000; 95% confidence interval, 1.000-1.010; p = 0.029). CONCLUSION: Our data suggested that PA-IgG at diagnosis could offer a useful predictor of response to first-line corticosteroid therapy for ITP.

[Concurrent subcutaneous panniculitis-like T-cell lymphoma and myelodysplastic syndrome with fibrosis].

A 66-year-old male presented with fever and erythema at our hospital, and leukoerythroblastosis, anemia, thrombocytopenia, and multiple low-density lesions in the moderately enlarged spleen were detected. Skin tissue revealed CD8+ T cells with the expression of cytotoxic molecule markers involving fat lobules, and subcutaneous panniculitis T-cell lymphoma (SPTCL) was diagnosed. The bone marrow displayed no infiltration of lymphoid tumor cells, but hyperplasia of granulocytes and megakaryocytes with grade 2 stromal fibrosis. In addition, the bone marrow exhibited diffuse 18F-fluorodeoxyglucose (FDG) accumulation on FDG positron-emission tomography/computed tomography (FDG-PET/CT). Although chemotherapy improved SPTCL, the patient died from leukocytosis with leukoerythroblastosis. We obtained negative results for the JAK2 V617F mutation, and CD34+ cells were elevated in the bone marrow compared with the levels at initial examination. The final diagnosis was concurrent myelodysplastic syndrome (MDS) with fibrosis and SPTCL. This report highlights that it is essential to consider MDS or other myeloproliferative neoplasms (MPN) as possible complications when malignant lymphoma complicates myelofibrosis in the absence of bone marrow infiltration of lymphoma cells. Perhaps, the assessment of clonal markers of MPN and FDG accumulation patterns in the bone marrow by FDG-PET/CT could enable differentiation.

[Ibrutinib therapy for a blastoid variant mantle cell lymphoma patient with early extranodal relapse after autologous stem cell transplantation].

A 65-year-old man with multiple lymphadenopathy presented to our hospital and was diagnosed with StageIVA blastoid-variant mantle cell lymphoma (MCL), with a Ki-67 index of 93%. Partial response was achieved after four courses of CHASER (cyclophosphamide, cytarabine, dexamethasone, etoposide, and rituximab) chemotherapy, and complete response was achieved after autologous stem cell transplantation (ASCT). Six months after ASCT, the MCL relapsed with occurrence of tumors one on the left upper arm and one in the cerebrum, which were proved to be resistant to the conventional chemotherapy and progressed rapidly. These tumors disappeared with scarring following the local irradiation (45 Gy). However, the unirradiated regions became enlarged. The bulky abdominal lesion was treated with local irradiation (41 Gy) combined with 560 mg of ibrutinib but still resulted in progressive disease 1 month after initiating the ibrutinib treatment. Finally, the patient died 5 months post-relapse. The prognosis of patients with blastoid-variant MCL with high Ki-67 index is extremely poor. Furthermore, the risk of central nervous system (CNS) involvement is very high. Therefore, ibrutinib maintenance therapy post ASCT might be a treatment option to prevent CNS involvement. Further efforts might be needed to improve the outcomes of blastoid-variant MCL with a high Ki-67 index.

[Successful treatment of myelodysplastic syndrome-associated autoinflammatory lymphedema with azacytidine].

An 84-year-old woman presented pancytopenia. She was diagnosed with myelodysplastic syndromes (MDS) with excess blasts-1, however, she declined treatment with azacitidine (AZA). Ten months later, bilaterally symmetrical, non-pitting edema appeared on the lower legs. A skin biopsy of the lower leg revealed lymphedema. The appearance and location of the lymphedema suggested an immunologic etiology; however, tests for autoimmune diseases yielded negative results. Therefore, a relationship between MDS and lymphedema was, therefore, speculated. Consequently, treatment with AZA was started, which led to marked improvement in both the lymphedema and pancytopenia. Based on the skin tissue pathology and the improvement in MDS after treatment with AZA, MDS-related autoinflammatory lymphedema was diagnosed.

[Successful diagnosis of lymphoplasmacytic lymphoma with IgG paraprotein using MYD88 L265P mutation analysis].

A 76-year-old woman presented to our hospital with leukocytosis and abnormal lymphocytes. M protein of the immunoglobulin G (IgG) type was detected using immunoelectrophoresis. A bone marrow biopsy revealed infiltration of small mature lymphocytes, lymphoplasmacytoid cells with Dutcher bodies, grape cells, and Russell bodies. The MYD88 L265P mutation was detected in the abnormal peripheral lymphocytes, and a diagnosis of lymphoplasmacytoid lymphoma was established. MYD88 L265P mutation analysis is useful for making a diagnosis of non-IgM lymphoplasmacytoid lymphoma because it enables the differentiation from other low-grade B-cell malignancies.

Saireito, a Japanese herbal medicine, alleviates leaky gut associated with antibiotic-induced dysbiosis in mice.

Antibiotics disrupt normal gut microbiota and cause dysbiosis, leading to a reduction in intestinal epithelial barrier function. Disruption of the intestinal epithelial barrier, which is known as "leaky gut", results in increased intestinal permeability and contributes to the development or exacerbation of gastrointestinal diseases such as inflammatory bowel disease and irritable bowel syndrome. We have previously reported on a murine model of intestinal epithelial barrier dysfunction associated with dysbiosis induced by the administration of ampicillin and vancomycin. Saireito, a traditional Japanese herbal medicine, is often used to treat autoimmune disorders including ulcerative colitis; the possible mechanism of action and its efficacy, however, remains unclear. In this study, we examined the efficacy of Saireito in our animal model for leaky gut associated with dysbiosis. C57BL/6 mice were fed a Saireito diet for the entirety of the protocol (day1-28). To induce colitis, ampicillin and vancomycin were administered in drinking water for the last seven consecutive days (day22-28). As previously demonstrated, treatment with antibiotics caused fecal occult bleeding, cecum enlargement with black discoloration, colon inflammation with epithelial cell apoptosis, and upregulation of pro-inflammatory cytokines. Oral administration of Saireito significantly improved antibiotics-induced fecal occult bleeding and cecum enlargement by suppressing inflammation in the colon. Furthermore, Saireito treatment ensured the integrity of the intestinal epithelial barrier by suppressing apoptosis and inducing cell adhesion proteins including ZO-1, occludin, and E-cadherin in intestinal epithelial cells, which in turn decreased intestinal epithelial permeability. Moreover, the reduced microbial diversity seen in the gut of mice treated with antibiotics was remarkably improved with the administration of Saireito. In addition, Saireito altered the composition of gut microbiota in these mice. These results suggest that Saireito alleviates leaky gut caused by antibiotic-induced dysbiosis. Our findings provide a potentially new therapeutic strategy for antibiotic-related gastrointestinal disorders.

Analysis of the Prevalence and Species of Anisakis nematode in Sekisaba, Scomber japonicus Caught in Coastal Waters off Saganoseki, Oita in Japan.

Anisakidosis is developed by ingesting Anisakis in marine fish, including the chub mackerel, Scomber japonicus, without proper pre-treatment such as cooking or freezing. Two sibling species of Anisakis are found in S. japonicus from Japanese waters, and the prevalence and species of Anisakis in the fish depend on the sea area. For example, Anisakis simplex sensu stricto (s.s.) is found in the Pacific stock of S. japonicus, whereas A. pegreffii is found in the Tsushima Warm Current stock. S.japonicus caught in the Bungo Channel, off the coast of Saganoseki in Oita Prefecture, which is branded as Sekisaba, inhabits a very limited area; however, the infection states of Anisakis found in Sekisaba remain unclear. In this study, we compared the infection states of Anisakis in Sekisaba with those in S. japonicus caught in the South Oita area and Nagasaki Prefecture. All Anisakis from the Nagasaki Prefecture were A. pegreffii, while most of them found in Sekisaba and fish from the South Oita area were A. simplex s.s. Interestingly, the prevalence of Anisakis in Sekisaba was significantly lower than that in the other two areas. This may reflect the fact that Sekisaba might belong to a distinct stock of S. japonicus, varying from other stocks.

L-asparaginase-induced Parotitis in an Elderly Patient with Acute Lymphoblastic Leukemia.

A 67-year-old woman received induction chemotherapy comprising vincristine, daunorubicin, cyclophosphamide, L-asparaginase and prednisolone for acute lymphoblastic leukemia with a common B-cell phenotype. The administration of L-asparaginase at 3,000 U/m2 for 6 days was planned. Before the fourth administration on day 16, left parotid swelling was identified along with increased serum amylase (991 U/L; 94% derived from salivary glands). An enlarged left parotid gland was apparent on computed tomography. The symptoms resolved after cessation of L-asparaginase, with serum amylase normalizing by day 20. This rare adverse event should be recognized as improving within a week after ceasing L-asparaginase.

Development of diffuse large B-cell lymphoma from duodenal type follicular lymphoma: a retrospective study of 23 cases.

The incidence and clinical characteristics of histological transformation (HT) from duodenal type follicular lymphoma (DFL) are unclear. A retrospective analysis was conducted to identify the incidence and clinical features of HT from DFL in 23 cases with DFL. The median follow-up duration was 4.6 years (range, 0.8-20 years). HT to diffuse large B-cell lymphoma was observed in 2 of 23 cases during follow-up (8.7%). One of two cases transformed at 21 months later with increased serum lactate dehydrogenase (LDH; 1655 U/L) and abdominal lymphadenopathy. Partial response was achieved after R-THP (pirarubicin)-COP therapy, but the disease progressed. The other case transformed at 8.3 years with an increase of serum LDH (4022 U/L), abdominal lymphadenopathy, and bone marrow involvement. The disease was refractory to DA-EPOCH-R and a high-dose methotrexate/cytarabine regimen. The patient received allogenic peripheral blood stem cell transplantation and finally achieved complete response. Both cases developed HT at nodal or other intestinal lesions with no progression of the primary duodenal lesion. No significant factors for the occurrence of HT were identified. Although the incidence is low, HT could occur in DFL with aggressive clinical manifestations.

Prognostic implications of TdT expression in acute myeloid leukemia with an intermediate-risk karyotype.

Terminal deoxynucleotidyl transferase (TdT) is expressed on precursor lymphoblastic neoplasms and some acute myeloid leukemia (AML) cells. The clinical impact of TdT expression on AML outcomes remains unclear. Here, we conducted a retrospective analysis to identify prognostic implications of TdT expression in AML with an intermediate-risk karyotype. Forty-eight cases of intermediate-risk AML were enrolled. TdT positivity was defined as expression on ≥ 10% of the gated cells. Of 48 cases, 12 (25%) were positive for TdT [median expression rate of TdT 0.9% (range 0-86.9%)]. No significant differences in patient characteristics or complete remission rate were observed between TdT-positive and TdT-negative cases. The probability of overall survival (OS) and event-free survival (EFS) at 1 year was not significantly different between TdT-positive and TdT-negative cases (OS: 58.3% vs. 65.2%, p = 0.32; EFS: 33.3% vs. 57.1%, p = 0.06). Relapse-free survival (RFS) probability at 1 year was significantly lower for TdT-positive than TdT-negative cases (10% vs. 71.3%, p = 0.002). Multivariate analyses revealed that TdT positivity was an independent significant adverse factor for RFS [hazard ratio: 3.309, 95% confidence interval: 1.334-8.209, p = 0.009]. Our results suggest that TdT expression is associated with increased risk of relapse in patients with intermediate-risk AML.