Kenji Tajika

IL‐6 and SCF exert different effects on megakaryocyte maturation

Megakaryocytic maturation has two aspects, nuclear maturation and cytoplasmic maturation, both of which are affected by several thrombopoietic cytokines. We cultured murine bone marrow cells separated by BSA velocity sedimentation which contained more immature megakaryocytes with lower ploidy in order to study the effects of rhIL‐6 and rmSCF on the two aspects of megakaryocyte maturation. During culture with rhIL‐6 or rmSCF for 4 d, the megakaryocytes underwent endomitosis, resulting in DNA polyploidization. These two cytokines had different effects on cytoplasmic maturation. Flow cytometry showed that the megakaryocytes cultured with rhIL‐6 became larger and had a more complex intracellular structure than those cultured with rmSCF. Morphological studies showed that the megakaryocytes cultured with rhIL‐6 were larger and more granular, whereas those cultured with rmSCF were smaller and more basophilic. rhIL‐6 promoted cytoplasmic process formation by the megakaryocytes, but rmSCF did not. Analysis of transcripts of PF‐4 and GPllb by RT‐PCR suggested that rmSCF kept more megakaryocytes at the protein synthesis stage than did rhIL‐6. Based on our findings, these cytokines exert different effects on megakaryocytic cytoplasmic maturational events.

A role of GAGs in ECM on morphogenesis of megakaryocytes.

The morphogenesis of megakaryocytes that results in the formation of cytoplasmic processes is thought to be the final maturation step before liberation of platelets. We studied the in vitro effects of glycosaminoglycans (GAGs) which are abundant in the bone marrow extracellular matrices, on the morphogenesis of murine megakaryocytes and compared them with those of thrombopoietic cytokines. Heparin, heparan sulfate, chondroitin‐6 sulfate, and dermatan sulfate promoted the formation of megakaryocytic processes. Hyaluronic acid failed to support this phenomenon, suggesting that sulfated GAGs in extracellular matrices are involved in the morphogenesis of megakaryocytes. Sulfated GAGs began to act on megakaryocytes with a higher ploidy (16N–32N) from 6 to 24 h after incubation, whereas neither rhIL‐6 nor rhIL‐11 affected this early phase. Our findings indicate that sulfated GAGs promote the morphogenesis of murine megakaryocytes and participate in thrombopoiesis in a different manner from that of cytokines such as rhIL‐6 and rhIL‐11.

Spontaneous bacterial peritonitis due to Clostridium perfringens in a patient with liver cirrhosis and pure red cell aplasia

SummaryA 63-year-old man with decompensated liver cirrhosis and pure red cell aplasia complained of pyrexia, abdominal distention and abdominal pain. A diagnosis of spontaneous bacterial peritonitis (SBP), Conn’s syndrome, was made upon the isolation of an anaerobeClostridium perfringens from both ascitic fluid and peripheral blood. The bacteria were found to be susceptible to piperacillin, and administration of the antimicrobial agent markedly improved his SBP. The anaerobes should be kept in mind as one of the possible pathogens of SBP, although anaerobic infection has been reported to be quite rare in the disease.

Prognostic impact of low allelic ratio FLT3-ITD and NPM1 mutation in acute myeloid leukemia

In the opinion of the European LeukemiaNet (ELN), nucleophosmin member 1 gene mutation (NPM1 mut)-positive acute myeloid leukemia (AML) with an fms-like kinase 3-internal tandem duplication (FLT3-ITD) allele ratio (AR) <0.5 (low AR) has a favorable prognosis, and allogeneic hematopoietic stem cell transplant (allo-HSCT) in the first complete remission (CR1) period is not actively recommended. We studied 147 patients with FLT3-ITD gene mutation-positive AML, dividing them into those with low AR and those with AR of ≥0.5 (high AR), and examined the prognostic impact according to allo-HSCT in CR1. Although FLT3-ITD AR and NPM1 mut are used in the prognostic stratification, we found that NPM1 mut-positive AML with FLT3-ITD low AR was not associated with favorable outcome (overall survival [OS], 41.3%). Moreover, patients in this group who underwent allo-HSCT in CR1 had a significantly more favorable outcome than those who did not (relapse-free survival [RFS] P = .013; OS P = .003). Multivariate analysis identified allo-HSCT in CR1 as the sole favorable prognostic factor (RFS P < .001; OS P < .001). The present study found that prognosis was unfavorable in NPM1 mut-positive AML with FLT3-ITD low AR when allo-HSCT was not carried out in CR1.