Mitogen-activated protein kinase pathway controls autoimmune regulator (AIRE) gene expression in granulo-monocyte colony stimulating factor (GM-CSF)-stimulated myelomonocytic leukemia OTC-4 cells.

Autoimmune regulator (AIRE) gene is a responsible gene for the rare autosomal recessive autoimmune disease: autoimmune-polyendocrinopathy-candidiasis ectodermal dystrophy (APECED). Although it has been reported that AIRE is expressed in the thymic epithelial cells and monocyte-dendritic cell lineage, the regulatory mechanisms of AIRE gene expression have as yet been poorly understood. Here we show that the expression of AIRE gene was induced in granulo-monocyte colony stimulating factor (GM-CSF)-stimulated myelomonocytic leukemia OTC-4 cells. In GM-CSF-stimulated OTC-4 cells, stat5 was not phosphorylated, while mitogen-activated protein kinases (MAPKs), including MAPK kinase (MEK) 1/2 and p38 MAPK, were phosphorylated, indicating activation of MAPK pathway. In addition, the expression of AIRE gene was inhibited by specific p38 MAPK inhibitor (SB203580), whereas the expression was rather enhanced by the MEK1/2 inhibitor (U0126), suggesting that AIRE gene expression is regulated by mitogen-activated protein kinase pathway.

Growth and apoptosis of human natural killer cell neoplasms: role of interleukin-2/15 signaling.

Interleukin (IL)-15 plays an important role in the survival of human natural killer (NK) cells. We investigated IL-2/15 signaling in NK cell neoplasms from five patients and in five cell lines (NK-92, KHYG-1, SNK-6, HANK1 and MOTN-1) compared to mature peripheral NK cells from 10 healthy subjects. Apoptosis of NK cell lines was prevented by addition of IL-15 in vitro. Blocking IL-2/15Rbeta on IL-2-stimulated NK-92 cells resulted in reduced expression of Bcl-X(L) and phosphorylated Stat5, which paralleled early apoptosis without altering Bcl-2 expression. These data add IL-2/15Rbeta to the list of factors important for the survival of NK cell neoplasms.

Chronic graft-versus-host disease following varicella-zoster virus infection in allogeneic stem cell transplant recipients.

We describe 2 allogeneic stem cell transplantation patients who developed chronic graft-versus-host disease (GVHD) after dermatomal varicella-zoster virus (VZV) infection. Localized zoster did not respond to oral valaciclovir but did resolve with intravenous aciclovir. However, skin eruptions, eye/oral dryness, and liver dysfunction were observed at the healing stage of localized zoster, suggesting development of GVHD. Intensification of immunosuppressive therapy was required to control GVHD. Quantitative real-time PCR for VZV DNA was used to distinguish liver involvement by chronic GVHD from visceral dissemination of VZV in 1 patient. VZV infection may trigger chronic GVHD after allogeneic stem cell transplantation.

Bestatin selectively suppresses the growth of leukemic stem/progenitor cells with BCR/ABL mRNA transcript in patients with chronic myelogeneous leukemia.

The in vitro effect of bestatin on Philadelphia (Ph) chromosome positive chronic myeloid leukemia (CML) was investigated using mature clonogenic cells and primitive stem cells derived from long-term culture-initiating cells (LTC-ICs). Individual colonies were grown in methycellulose culture (clonogenic cells) and after 5 weeks, LTC (colonies derived from LTC-ICs) were individually isolated. DNA isolated from these clonogenic colonies was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis to detect BCR/ABL mRNA transcripts b3a2 and b2a2. At the mature hematopoietic progenitor cell level, almost all (20/21) colonies, including both erythroid and myeloid progenitors, were leukemic, i.e. BCR/ABL mRNA positive. Although normal progenitors were able to grow in the presence of bestatin, even at the most primitive progenitor cell level (LTC-ICs), the number of leukemic clones gradually decreased. Furthermore, bestatin suppressed the outgrowth of leukemic clones more frequently than control LTC without any effect on the growth of normal clones. These results indicate that bestatin, at levels that can be obtained by per os administration clinically, suppresses only Ph-positive leukemic clones without affecting normal hematopoiesis. Based on these results, we suggest that bestatin has the potential to provide another treatment for patients with CML.

Detection of human herpesvirus-8 in peripheral blood mononuclear cells from adult Japanese patients with multicentric Castleman's disease.

Human herpesvirus-8 (HHV-8) encodes viral homologues of cellular genes, including viral interleukin 6 (vIL-6), which induces endogenous human IL-6 (hIL-6) secretion. Unregulated overproduction of hIL-6 in lymph nodes (LN) is thought to be responsible for the systemic manifestations of multicentric Castleman's disease (MCD). In the present study, we assessed the presence of HHV-8 and HHV-8-encoded viral homologues in LN and peripheral blood mononuclear cells (PBMC) from adult Japanese patients with MCD. HHV-8 DNA was amplified by nested polymerase chain reaction (PCR) and was detected in LN from 13 out of 16 MCD patients (81%). HHV-8 DNA was also detected in PBMC from six out of seven patients (86%) whose LN were positive for HHV-8 DNA. Because mRNA could not be successfully extracted from LN sections that were either formalin-fixed or embedded in paraffin, we examined the expression of mRNA for HHV-8-encoded viral homologues, such as vIL-6, vBCL-2, vCyclin-D and viral G-protein-coupled receptor (vGPCR) by nested reverse transcription (RT)-PCR in PBMC from 10 MCD patients. However, mRNA of these HHV-8-encoded viral homologues was not detected in any patients tested. Although our results do not indicate a role for HHV-8-encoded viral homologues in the pathogenesis of MCD, they do suggest that HHV-8 infection may be associated with MCD in adult Japanese patients.