Masayoshi Minegishi

Alterations of the p53, p21, p16, p15 and RAS genes in childhood T-cell acute lymphoblastic leukemia

We investigated the alterations of the p53, p21, p16, p15 and RAS genes in childhood T-cell acute lymphoblastic leukemia (T-ALL) and T-ALL cell lines by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing. Mutations of the p53 gene were found in three of 57 (5%) patients at diagnosis, one of 14 (7%) patients at relapse and in 12 of 18 (67%) cell lines. In these 12 cell lines, four had more than two mutations of the p53 gene. The p53 mutations were found in four of five cell lines whose original fresh leukemic cells were simultaneously examined original fresh leukemic cells. However, only one of the four fresh leukemic cells had the same mutation. All patients with p53 mutations in the course of disease died. Mutations of the p21 gene were not identified in 71 fresh samples and in 18 cell lines. N-RAS mutations were found in two of 57 (4%) fresh T-ALL patients at diagnosis, and four of 18 cell lines (22%), whereas no mutations were detected in any samples at relapse. Alterations of the p16 gene were found in 18 of 47 (38%) patients at diagnosis and in seven of 14 (50%) at relapse. These differences were not statistically significant. There were no differences in the frequency of alteration of the p16 and p15 genes between event-free patients and the remaining patients. Furthermore, we found the methylation of p16 gene in three of seven patients lacking homozygous deletions, suggesting higher frequency of p16 inactivation than previous reports in T-ALL. Interestingly, we found that one allele is inactivated by methylation and another allele had nonsense mutation in one cell line (KOPT-KI), resulting in loss of protein expression of p16. This type of p16 inactivation has not been so far reported in leukemia. We conclude that, (1) p53 mutations are infrequent at diagnosis but tend to be associated with poor clinical outcome; (2) RAS and p21 mutations may not be involved in the pathogenesis of T-ALL; (3) not only frequent alterations of p16 and p15 genes but also methylation of p16 gene are involved in initiating the leukemogenesis of T-ALLs, and (4) these 5 genes are independently involved in T-ALL.

THE AH RECEPTOR IS NOT INVOLVED IN 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN-MEDIATED APOPTOSIS IN HUMAN LEUKEMIC T CELL LINES

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a common environmental pollutant causing public concern. Its toxic effects include disruption of the immune, endocrine, and reproductive systems, impairment of fetal development, carcinogenicity, and lethality in rodents. Here, we report that TCDD induces apoptosis in two cultured human leukemic lymphoblastic T cell lines. This cell death was found not to be dependent on an aryl hydrocarbon receptor and to be inhibited by the inhibitor of tyrosine kinases and caspases. Apoptosis-linked c-Jun N-terminal kinase is rapidly activated in these cells by the treatment with TCDD. A dominant-negative mutant of c-Jun N-terminal kinase prevented cell death in the treatment with TCDD. Furthermore, TCDD decreases the Bcl-2 protein level in these cell lines. These findings will help in the understanding of the molecular mechanism underlying TCDD-mediated immunotoxicity.

Subacute panencephalitis associated with chronic graft-versus-host disease

SummaryA unique form of subacute panencephalitis developed in a child with aplastic anemia 8 months after an allogeneic bone marrow transplantation (BMT). It was characterized by parenchymal infiltration of CD3 lymphocytes, a marked increase in the number of microglia strongly expressing HLA-DR antigens in both the gray and white matter, and diffuse degeneration of the cerebral white matter. The onset of neurological symptoms coincided with the development of chronic systemic graft-versus-host disease (GVHD). Cellular infiltrates in the CNS lesions were exclusively CD3 lymphocytes intermingled with a small number of monocytes labeled with CD68. There was a preponderance of cells of the CD45RB phenotype. The pathological changes in visceral organs were consistent with those of chronic GVHD. In addition, scrutiny of immunohistochemistry disclosed sparse infiltration of CD3 lymphocytes and diffuse gliosis in the cerebral white matter of another child with chronic GVHD who died 9 months after allogeneic BMT. These cases are suggestive of a potential risk of CNS involvement in GVHD.

Deficient activity of von Willebrand factor-cleaving protease in patients with Upshaw-Schulman syndrome.

We identified unusually large von Willebrand factor (vWF) multimers caused by deficient activity of vWF-cleaving protease in 2 patients with Upshaw-Schulman syndrome. The autoantibodies that inhibited the protease activity were not detected in the plasma of either patient. Periodic fresh-frozen plasma transfusion was effective for management of the hemolysis and thrombocytopenia. We detected enriched enzyme activity in a particular plasma fraction, although molecular cloning of this specific protease is needed to determine a more detailed pathogenesis and to develop new therapeutic approaches.

Development of a Multi-Step Leukemogenesis Model of MLL-Rearranged Leukemia Using Humanized Mice

Mixed-lineage-leukemia (MLL) fusion oncogenes are intimately involved in acute leukemia and secondary therapy-related acute leukemia. To understand MLL-rearranged leukemia, several murine models for this disease have been established. However, the mouse leukemia derived from mouse hematopoietic stem cells (HSCs) may not be fully comparable with human leukemia. Here we developed a humanized mouse model for human leukemia by transplanting human cord blood-derived HSCs transduced with an MLL-AF10 oncogene into a supra-immunodeficient mouse strain, NOD/Shi-scid, IL-2Rγ−/− (NOG) mice. Injection of the MLL-AF10-transduced HSCs into the liver of NOG mice enhanced multilineage hematopoiesis, but did not induce leukemia. Because active mutations in ras genes are often found in MLL-related leukemia, we next transduced the gene for a constitutively active form of K-ras along with the MLL-AF10 oncogene. Eight weeks after transplantation, all the recipient mice had developed acute monoblastic leukemia (the M5 phenotype in French-American-British classification). We thus successfully established a human MLL-rearranged leukemia that was derived in vivo from human HSCs. In addition, since the enforced expression of the mutant K-ras alone was insufficient to induce leukemia, the present model may also be a useful experimental platform for the multi-step leukemogenesis model of human leukemia.

Successful umbilical cord blood transplantation from an unrelated donor for a patient with Epstein–Barr virus-associated hemophagocytic lymphohistiocytosis

We report a case of a 5-year-old girl with EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH) who underwent cord blood (CB) stem cell transplantation (CBSCT) from an unrelated donor. The patient presented with persistent high-grade fever and hepatosplenomegaly. Because the disease was refractory to immunochemotherapy according to the HLH94 protocol, she received 2.0 × 107 CB nucleated cells/kg body weight (BW) after conditioning with BU/CY/etoposide. No acute GVHD developed, using FK506 for prophylaxis. The neutrophil count reached >0.5 × 109/l by day 21 and the platelet count reached >50 × 109/l by day 84. The patient recovered well with sequelae of neurological deficits more than 10 months after receiving CBSCT, without showing evidence of HLH or chronic GVHD. Real-time PCR proved applicable for estimation of the EBV load in PBMC of the patient. We conclude that CBSCT may be indicated for some cases of refractory EBV-HLH, who have no HLA-matched siblings and are therefore dependent on unrelated marrow donors. Bone Marrow Transplantation (2001) 27, 883–886.

Quality assessment of umbilical cord blood units at the time of transplantation

Total nucleated cell (TNC) count, CD34+ cell count, colony-forming unit-granulocyte–macrophage (CFU-GM) content, and cell viability impact the outcome of umbilical cord blood (UCB) transplantation. Assessments of unit quality have usually been provided by cord blood banks (CBBs), but it is unclear whether pre-freezing tests or pre-transplant release tests performed by CBBs are reproducible. The aim of this study was to compare the UCB characteristics analyzed at the site of infusion of the UCB with those provided by CBBs. Samples were taken from 54 UCB units for assessment of post-thaw characteristics. TNC counts and CD34+ cell contents measured at our hospital before infusion showed good correlations with values assessed in pre-freezing tests (r = 0.900 and 0.943, respectively) and pre-transplant release tests (r = 0.829 and 0.930, respectively). Our data reveal that the TNC counts and CD34+ cell contents determined by pre-freezing and pre-transplant release tests, which are the most important UCB unit selection criteria, accurately reflected the quality of infused UCB units. However, CFU-GM content was poorly correlated (r = 0.560 and 0.606). Correlation of post-thaw cell viabilities measured before infusion and during the pre-transplant release tests was also poor (r = 0.308). We suggest that the TNC count and CD34+ cell content estimated before cryopreservation and in pre-transplant release tests provided by CBBs are reproducible and can assist the transplant physicians in selection of appropriate UCB units.

Epstein-Barr Virus-Associated Lymphoproliferative Disorder after Unrelated Bone Marrow Transplantation in a Young Child with Wiskott-Aldrich Syndrome

We report a case of a 16-month-old Wiskott-Aldrich syndrome (WAS) patient with a WASP gene mutation who received human leukocyte antigen (HLA)-matched, unrelated allogeneic bone marrow transplantation (BMT) followed by an Epstein-Barr virus-associated lymphoproliferative disorder (EB-LPD), diagnosed by clinical findings, polymerase chain reaction detection of the EB virus genome, and spontaneous lymphocyte proliferation of donor cell origin. EB-LPD is one of frequent lethal complications in HLA-mismatched or unrelated BMT in this syndrome. Adoptive immunotherapy with donor leukocyte transfusion, including appropriate numbers of CD3-positive T cells, was effective for the EB-LPD, achieving almost complete recovery 1 year later without any findings of graft-versus-host disease.

Immunological reconstitution by allogeneic bone marrow transplantation in a child with the X-linked hyper-IgM syndrome

Abstract A successful transplantation of sibling marrow in a patient with the X-linked hyper-IgM syndrome is reported. Engraftment of HLA-identical marrow cells was obtained, although complicated by grade I acute graft-versus-host disease. Expression of the CD40 ligand (CD40L, CD154) by activated T-cells from the recipient remained at low levels until 10 months after the transplantation, but then normalized. The patient is now fully competent in immune function without any episodes of severe infection 24 months later. Conclusion Allogeneic bone marrow transplantation is a reasonable therapeutic option for X-linked hyper-IgM syndrome if HLA-matched family donors are available. Whether dysregulation of CD40L expression causes post-transplant immunological abnormalities remains to be clarified.

Successful treatment of steroid-resistant severe acute GVHD with 24-h continuous infusion of FK506.

We report our findings in two cases of steroid-resistant severe acute GVHD after allogeneic BMT successfully treated with FK506 (tacrolimus). An 18-year-old female (patient 1) who underwent BMT from an HLA-identical sibling for ALL in first CR, developed generalized erythema and profuse watery diarrhea, which progressed to acute GVHD of grade III severity, resistant to steroid control. After continuous 24-h administration of FK506, the diarrhea improved within 10 days. Patient 2, a 9-year-old girl with AML who underwent unrelated BMT, had skin, gut and liver lesions of acute GVHD grade IV, which did not respond to high-dose steroid therapy. They were controlled, however, by continuous intravenous infusion of FK506. Both patients are still surviving after more than 1 year without any acute GVHD sequelae or signs of chronic illness. The adverse effects of FK506 were mild and tolerable in both cases. Comparison of our findings with those in the literature suggests that it is important to give FK506 at plasma concentrations as high as 25–35 ng/ml by continuous intravenous infusion for extended periods to control steroid-resistant severe acute GVHD.