Hiroji Okawa

WASP is involved in proliferation and differentiation of human haemopoietic progenitors in vitro

The Wiskott‐Aldrich syndrome (WAS) is an X‐linked recessive disorder characterized by thrombocytopenia, immunodeficiency and eczema. X‐linked thrombocytopenia (XLT) is a mild form of WAS with isolated thrombocytopenia. Both phenotypes are caused by mutation of the Wiskott‐Aldrich syndrome protein (WASP) gene. In this study we investigated the role of WASP in the differentiation of CD34‐positive (CD34+) cells isolated from the bone marrow of patients with WAS (n = 5) or with XLT (n = 4). Megakaryocyte colony formation was significantly decreased in patients with WAS when compared with normal controls. The formation of granulocyte‐macrophage colonies and erythroid bursts were also decreased in WAS patinets. In contrast, in XLT patients, formation of all these colonies was normal. However, in vitro proplatelet formation of megakaryocytes induced by thrombopoietin was markedly decreased in both XLT and WAS. Electron microscopic examination revealed that megakaryocytes obtained from WAS or XLT patients grown in vitro had abnormal morphologic features, which seemed to be caused by defective actin cytoskeletal organization, including labyrinth‐like structures of the demarcation membrane system and deviated distribution of the α‐granules and demarcation membrane system. These observations indicate that WASP is involved in the proliferation and differentiation of CD34+ haemopoietic progenitor cells probably by its participation in signal transduction and in the regulation of the cytoskeleton.

The increase of non-MHC-restricted cytotoxic cells (γδ-TCR-bearing T cells or NK cells) and the abnormal differentiation of B cells in Wiskott-Aldrich syndrome

The objective of this study was to analyze the configuration of the lymphocytes in Wiskott-Aldrich syndrome (WAS) by studying the surface antigens from nine cases using dual-color immunofluorescence analysis. All the patients showed the increase of non-MHC-restricted cytotoxic cells, namely CD3+WT31−δTCS1+ (γδ-T cell receptor (TCR)-bearing cells) and/or CD16+ natural killer cells. The γδ-TCR+ cells of WAS, however, were unique since they did not express CD5, which is present on ordinary γδ-TCR+ cells. A reduced number of CD4+ cells and an increased percentage of CD11b+Leu7+ cells within a CD8+ subset were observed in all cases. With regard to B cell subpopulations, most cases showed reduced FcϵR2-bearing B cells, despite an elevated serum IgE.

Consensus guideline for diagnosis and treatment of childhood idiopathic thrombocytopenic purpura.

A practice guideline aimed at standardizing the treatment for childhood idiopathic thrombocytopenic purpura (ITP) is presented. This consensus guideline is based on a survey carried out via a questionnaire prepared by the ITP Committee of the Japanese Society of Pediatric Hematology and sent to society members. The survey questionnaire included questions on the diagnosis of ITP submitted for the purpose of revising the ITP diagnostic guideline prepared in 1990 by the Research Group for Intractable Hematopoietic Disorders; a revised diagnostic guideline also is presented.

Epstein-Barr Virus-Associated Malignant Lymphoma with Macroamylasemia and Monoclonal Gammopathy in a Patient with Wiskott-Aldrich Syndrome

A 1-year-old boy with Wiskott-Aldrich Syndrome (WAS) who developed malignant lymphoma is described. He showed various complications such as atypical lymphocytosis, disseminated intravascular coagulation (DIC), intracranial hemorrhage, macroamylasemia, and monoclonal gammopathy (immunoglobulin A kappa chain). Epstein-Barr virus (EBV) DNA was detected in the tumor tissue, and the monoclonality of B cells from the tumor tissue was established. EBV-associated lymphoma is frequently observed in immunocompromised patients including those with WAS. The development of macroamylasemia, which is rare in childhood, is discussed in relation to lymphoma and monoclonal gammopathy. This case is unique in that the EBV-associated malignant lymphoma developed at an early age and was accompanied by macroamylasemia.

Three novel mutations in the interleukin-2 receptor γ chain gene in four Japanese patients with X-linked severe combined immunodeficiency

Three novel mutations in the IL-2Rγ chain gene were identified in four Japanese patients with X-linked severe combined immunodeficiency by direct sequence analysis of polymerase chain reaction (PCR) amplified DNA fragments.

Characterization of extramedullary tumors in a case of Ph-positive chronic myelogenous leukemia: Possible involvement of immature T lymphocytes

A 42-year-old male with chronic myelogenous leukemia (CML) developed acute transformation associated with subcutaneous tumors. Histopathologic examinations of the tumors were done on two occasions; the first study revealed reticulum cell sarcoma-like features, and the second suggested a blastoma. Chromosomal analysis showed that the cells of the tumors originated from the CML clone. The cells had a negative reaction for myeloperoxidase by electron microscopy. Furthermore, biochemical and surface marker studies revealed that the tumor cells contained a significant terminal transferase activity. However, they did not express E- or EAC-rosette receptors, Ia-like antigens, or common ALL antigens.

A Case Report of T-cell Lymphoma With Suppressor Phenotype and Helper Function for Immunoglobulin Synthesis

A patient with T‐cell lymphoma is presented. The morphologic features of a biopsied lymph node were consistent with adult T‐cell lymphoma with hypergammaglobulinemia, and most of the lymph node cells were reactive with monoclonal antibody OKT8, which detects suppressor/cytotoxic T lymphocytes. However, in a pokeweed mitogen‐driven test system in which the capability of T lymphocytes to help or suppress the differentiation of B lymphocytes is measured, the lymphoma cells induced immunoglobulin synthesis of B lymphocytes, thus providing helper function. As far as we know, this is the first report on T‐cell lymphoma having suppressor phenotype and helper function for immunoglobulin synthesis.

CLINICAL AND BIOLOGICAL ASPECTS OF ACUTE LYMPHOBLASTIC LEUKEMIA IN 62 INFANTS: RETROSPECTIVE ANALYSIS OF THE TOKYO CHILDREN'S CANCER STUDY GROUP

Abstract Background: As a first step to formulate a new treatment strategy for refractory acute lymphoblastic leukemia (ALL) in infants, clinical results and immunophenotypic and cytogenetic data were analyzed and compared with those from overseas.

Phenotypical and functional heterogeneity of the large granular lymphocytes increased after various treatments in a patient with combined immunodeficiency

A boy with combined immunodeficiency having low natural killer (NK)-cell activity received thymopoietin pentapeptide (TP-5) treatment, transplanted with T cell-depleted HLA-haploidentical bone marrow (BMT) cells from his father and with thymus tissue from an infant at different times during the first year of life. He showed a marked increase in large granular lymphocytes (LGL) both during the treatment with TP-5 and after BMT. The LGL generated following TP-5 injection had a T3+ Leu 11− surface phenotype and low NK activity. In contrast, the LGL appearing after BMT showed T3−, Leu7+, and/or Leu11+ surface phenotypes, had high NK- and K-cell activities, and were lymphokine-activated killer (LAK)-cell precursors. These killer activities were assigned to the Leu7− Leu11+ subset and proved to be of recipient origin. LGL proliferation following BMT was accompanied by neutropenia, which was improved in association with a reduction in the number of LGL and the appearance of T cells of BMT donor origin following thymus transplantation. This suggested the inhibition of granulopoiesis by the LGL and anin vitro study revealed that the Leu7+ Leu11− subset of LGL suppressed the growth of granulocyte/macrophage colony-forming units. These results indicated that phenotypically different LGL could be generated by different treatments and that the LGL showing NK activity were distinct from those regulating granulopoiesis. It was also suggested that the generation of LGL was controlled by T cells.

Cell cycle-related expression of surface antigens on myelomonocytic leukemia cells

We investigated the relationship between the expression of surface antigens and the cell cycle phase in leukemic cells from cell lines and one patient using two-color flow cytometry, in order to determine the reason for the uneven expression of some markers which frequently leads to equivocal results as to leukemic phenotyping. As a result, it was demonstrated that monocyte-related differentiation markers, including I2, My4, Mo1 and Mo2, on monocytoid leukemic cells are preferentially expressed at the G0/G1 phase. Consequently, it is expected that the positivities for such markers vary with the proliferation status of the leukemic cells.