Key Points KIT exon 17 mutation is a poor prognostic factor in AML patients with RUNX1-RUNX1T1, but not in those with CBFB-MYH11. NRAS mutation is a poor prognostic factor in AML patients with CBFB-MYH11.

Recent sequencing studies demonstrated the MYD88 L265P mutation in more than 70% of primary central nervous system lymphomas (PCNSL), and the clinical significance of this mutation has been proposed as diagnostic and prognostic markers in PCNSL. In contrast, mutational analyses using cell‐free DNAs have been reported in a variety of systemic lymphomas. To investigate how sensitively the MYD88 L265P mutation can be identified in cell‐free DNA from PCNSL patients, we carried out droplet digital PCR (ddPCR) and targeted deep sequencing (TDS) in 14 consecutive PCNSL patients from whom paired tumor‐derived DNA and cell‐free DNA was available at diagnosis. The MYD88 L265P mutation was found in tumor‐derived DNA from all 14 patients (14/14, 100%). In contrast, among 14 cell‐free DNAs evaluated by ddPCR (14/14) and TDS (13/14), the MYD88 L265P mutation was detected in eight out of 14 (ddPCR) and in 0 out of 13 (TDS) samples, implying dependence on the detection method. After chemotherapy, the MYD88 L265P mutation in cell‐free DNAs was traced in five patients; unexpectedly, the mutations disappeared after chemotherapy was given, and they remained undetectable in all patients. These observations suggest that ddPCR can sensitively detect the MYD88 L265P mutation in cell‐free DNA and could be used as non‐invasive diagnostics, but may not be applicable for monitoring minimal residual diseases in PCNSL.

Tissue accumulation of polymorphonuclear neutrophils (PMN) in Inflammatory Bowel disease (IBD) might be, in part, due to a delay in apoptotic processes associated with the effects of their specific growth factors and inflammatory cytokines. We addressed this hypothesis by examining the activity of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage CSF (GM-CSF) in the organ culture supernatants of colonic mucosal specimens and their regulatory effects on PMN apoptosis in patients with IBD. The contents of G-CSF and GM-CSF in the supernatants were measured by the enzyme-linked immunosorbent assays and PMN apoptosis was evaluated by acridine orange/ethidium bromide staining, respectively. Mucosal specimens obtained from patients with active IBD exhibited higher levels of G-CSF and GM-CSF activity than controls. Notably, the levels of G-CSF activity were approximately 1000-fold higher than those of GM-CSF activity. Freshly isolated PMN showed a time-related increase in the proportion of cells with characteristic features of apoptosis when they were incubated with the culture medium alone and exposure of PMN to recombinant G-CSF and GM-CSF caused a concentration-dependent inhibition of apoptosis. Incubation of PMN with the supernatants from patients with active IBD induced an inhibitory effect on PMN apoptosis; this effect was abrogated to a significant degree by pre-incubation of the supernatants with anti-G-CSF serum. This study suggests that PMN apoptosis may be delayed under the influence of soluble mediators, especially G-CSF, in the microenvironment of IBD-affected mucosa, thus providing possible mechanisms for tissue accumulation of PMN in IBD.

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CD4Foxp3 regulatory T cells (Treg) are a subpopulation of T cells, which regulate the immune system and enhance immune tolerance after transplantation. Donor-derived Treg prevent the development of lethal acute graft-versus-host disease (GVHD) in murine models of allogeneic hematopoietic stem cell transplantation. We recently demonstrated that a single treatment of the agonistic antibody to DR3 (death receptor 3, αDR3) to donor mice resulted in the expansion of donor-derived Treg and prevented acute GVHD, although the precise role of DR3 signaling in GVHD has not been elucidated. In this study, we comprehensively analyzed the immunophenotype of Treg after DR3 signal activation, demonstrating that DR3-activated Treg (DR3-Treg) had an activated/mature phenotype. Furthermore, the CD25Foxp3 subpopulation in DR3-Treg showed stronger suppressive effects in vivo. Prophylactic treatment of αDR3 to recipient mice expanded recipient-derived Treg and reduced the severity of GVHD, whereas DR3 activation in mice with ongoing GVHD further promoted donor T-cell activation/proliferation. These data suggest that the function of DR3 signaling was highly dependent on the activation status of the T cells. In conclusion, our data demonstrated that DR3 signaling affects the function of Treg and T-cell activation after alloantigen exposure in a time-dependent manner. These observations provide important information for future clinical testing using human DR3 signal modulation and highlight the critical effect of the state of T-cell activation on clinical outcomes after activation of DR3.