Yumi Tone

Clinical Significance of Cloned Expansion and CD5 Down-Regulation in Epstein-Barr Virus (EBV)- Infected CD8 + T Lymphocytes in EBV-Associated Hemophagocytic Lymphohistiocytosis

Epstein-Barr virus (EBV) is the pathogen that most commonly triggers infection-associated hemophagocytic lymphohistiocytosis (HLH) and ectopically infects CD8(+) T cells in EBV-associated HLH (EBV-HLH). We recently described an EBV-HLH patient who had a clonally expanded population of EBV-infected CD8(+) T cells with CD5 down-regulation. To determine whether this finding could serve as a useful marker for EBV-HLH, we investigated 5 additional patients. We found a significant increase in the subpopulation of CD8(+) T cells with CD5 down-regulation and bright human leukocyte antigen (HLA)-DR expression in all patients with EBV-HLH but not in patients with infectious mononucleosis or in control subjects. Such T cells were frequently found to be larger cells that stained positive for a specific T cell receptor VB. We also demonstrated that those cells were the major cellular target of EBV, and their numbers progressively declined in parallel with the serum ferritin levels. All together, our findings reveal the immunophenotypic characteristics of EBV-infected CD8(+) T cells and may provide a valuable tool for the diagnosis of EBV-HLH.

Skin infiltration of CD56bright CD16- natural killer cells in a case of X-SCID with Omenn syndrome-like manifestations

We observed a patient with X‐linked severe combined immunodeficiency (X‐SCID) with Omenn syndrome‐like manifestations. X‐linked inheritance, absence of CD132 expression and impaired response to interleukin‐2 (IL‐2) indicated that the case is typical of X‐SCID due to γc defect. However, this case was unusual in that circulating natural killer (NK) cells were increased and nearly half of these NK cells exhibited the CD56bright CD16− phenotype. A missense mutation was found within exon 5 of the IL2RG gene. The identical mutation was detected within NK, CD4+ T and B cells. Engraftment of maternally derived NK cells or gene reversion was ruled out. The erythroderma‐like skin lesion was characterized by infiltration of the dermis by CD56bright NK cells admixed with CD1a+ dendritic cells (DC). Expression of mRNA for inflammatory cytokines was significantly enhanced within the skin. This may be the first human case to demonstrate that close cell‐to‐cell contact between DC and NK cells provides an effective alternative pathway for NK cell differentiation/activation in vivo.

Immunophenotypic analysis of Epstein–Barr virus (EBV)‐infected CD8+ T cells in a patient with EBV‐associated hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a severe and often fatal condition characterized by uncontrolled activation of T cells and macrophages. In Epstein–Barr virus (EBV)‐associated HLH (EBV‐HLH), the pathogenic roles of ectopic EBV infection in the T‐cell population and of clonal proliferation of EBV‐infected T cells has been described. However, the immunophenotype of EBV‐infected T cells has not been fully characterized. Here we describe a case of EBV‐HLH presenting with a massive clonal proliferation of CD8+ T cells with TCR VB14. Analysis of in situ hybridization for EBV‐encoded small RNA1 showed that only CD8+ T cells harbored EBV in this patient. The EBV‐infected TCR VB14+ CD8+ T cells exhibited unique immunophenotypic features including lacked CD5 expression and a markedly bright expression of HLA‐DR. After initiation of treatment with prednisolone, etoposide, and cyclosporin A, the percentage of infected cells declined progressively in parallel with other serum markers such as ferritin. These findings suggest that lacking expression of CD5 on CD8+ T cells with specific TCR VB may serve as a useful marker of dysregulated T‐cell activation and proliferation in EBV‐HLH.

Colchicine-responsive chronic recurrent multifocal osteomyelitis with MEFV mutations: a variant of familial Mediterranean fever?

*KURAに登録されているコンテンツの利用については,著作権法に規定されている私的使用や引用などの範囲内で行ってください。 *著作権法に規定されている私的使用や引用などの範囲を超える利用を行う場合には,著作権者の許諾を得てください。ただし,著作権者 から著作権等管理事業者(学術著作権協会,日本著作出版権管理システムなど)に権利委託されているコンテンツの利用手続については ,各著作権等管理事業者に確認してください。 Title Colchicine-responsive chronic recurrent multifocal osteomyelitis with MEFV mutations: A variant of familial Mediterranean fever? Author(s) Shimizu, Masaki; Tone, Yumi; Toga, Akiko; Yokoyama, Tadafumi; Wada, Taizo; Toma, Tomoko; Yachie, Akihiro Citation Rheumatology, 49(11): 2221-2223

Clonotypic analysis of T cell reconstitution after haematopoietic stem cell transplantation (HSCT) in patients with severe combined immunodeficiency

Haematopoietic stem cell transplantation (HSCT) is performed for treatment of a broad spectrum of illnesses. Reconstitution of an intact immune system is crucial after transplantation to avoid infectious complications, and above all, the establishment of T cell receptor (TCR) diversity is the most important goal in the procedure. Until recently, little has been known of the mechanism of T cell reconstitution in the very early period after HSCT. In this study, we analysed TCR repertoires sequentially in four patients with severe combined immunodeficiency (SCID) before and after HSCT. In all patients, the TCR repertoires were extremely abnormal before HSCT, whereas after transplantation there was progressive improvement in TCR diversity, based on analysis of the TCR Vβ repertoire and CDR3 size distributions. Somewhat unexpectedly, there was a significant but transient expansion of TCR diversity 1 month after transplantation in all cases. Clonotypic analysis of TCRs performed in one case showed that many T cell clones shared identical CDR3 sequences at 1 month and that the shared fraction decreased progressively. These results indicate that early expansion of TCR diversity may reflect transient expansion of pre‐existing mature T cells from the donor blood, independent of de novo T cell maturation through the thymus.

Enhanced exon 2 skipping caused by c.910G>A variant and alternative splicing of MEFV genes in two independent cases of familial Mediterranean fever

Most reported cases of familial Mediterranean fever (FMF) involve missense mutations of MEFV concentrated within exon 10. We experienced two independent pedigrees of a unique variant in the MEFV gene that might cause excessive exon 2 skipping due to enhanced alternative splicing. In this study, we tried to elucidate the molecular mechanism of the MEFV variant as a cause of the FMF phenotype. Peripheral blood was obtained from volunteers and two patients with homozygous c.910G>A variant of the MEFV gene. MEFV messenger RNA (mRNA) expression patterns in mononuclear cells and granulocytes were compared using forward and reverse primers from exons 1 and 3, respectively. Expression profiles of pyrin were examined by transfecting wild-type and variant MEFV genes into HEK293T cells. Expression of normal-sized mRNA was extremely reduced in these patients, whereas that of aberrant short mRNA, deleting exon 2 (Δex2), was significantly increased. Immunohistochemical and immunoblotting analyses revealed a truncated immunoreactive pyrin protein in cells transfected with Δex2 cDNA. The MEFV gene c.910G>A variant results in accelerated aberrant splicing with abnormal protein size, presumably leading to anomalous pyrin function. This is the first report to show that an MEFV variant other than missense mutation is responsible for the FMF phenotype.

Reactive Peripheral Blood Plasmacytosis in a Patient with Acute Hepatitis A

Reactive plasmacytosis is a transient expansion of plasma cell progenitors and precursors. This rare condition has been reported to occur mainly in infections and tumors. We describe a case of acute hepatitis A presenting with marked peripheral blood plasmacytosis. Plasma cells made up 27.5% of the mononuclear cells and had the immunophenotype CD10-CD19+CD20-CD21-CD23-CD34-CD38++HLA-DR+. Although the level of interleukin 6 was not increased, the presence of activated T-cells with an inverted CD4/CD8 ratio and high levels of soluble interleukin 2 receptor and neopterin indicated a marked immune response to acute hepatitis A. The patient’s plasma cells had almost disappeared from the blood by hospital day 16. This report may represent the first described case of reactive peripheral blood plasmacytosis in acute hepatitis A.

Flow cytometric analysis of skin blister fluid induced by mosquito bites in a patient with chronic active Epstein-Barr virus infection

In chronic active Epstein–Barr virus (EBV) infection (CAEBV), ectopic EBV infection has been described in T or natural killer (NK) cells. NK cell-type infection (NK-CAEBV) is characterized by large granular lymphocytosis, high IgE levels and unusual reactions to mosquito bites, including severe local skin reactions, fever and liver dysfunction. However, the mechanisms underlying these reactions remain undetermined. Herein, we describe a patient with NK-CAEBV whose blister fluid after mosquito bites was analyzed. The patient exhibited significant increases in the percentage of CD56+ NK cells in the fluid compared with a simple mosquito allergy, in which the majority of infiltrated cells were CD203c+ cells, indicating basophils and/or mast cells. His fluid also contained CD203c+ cells, and his circulating basophils were activated by mosquito extracts in vitro. These results suggest that CD203c+ cells as well as NK cells may play pathogenic roles in the severe skin reactions to mosquito bites in NK-CAEBV.