Fine mapping of an apparently targeted latent human herpesvirus type 6 integration site in chromosome band 17p13.3

An unusually high level of latent HHV-6 infection has been documented in the peripheral blood and/or bone marrow cells of a small group of patients with predominantly malignant lymphoid disorders, and in at least one healthy individual. We have shown previously in peripheral blood mononuclear cells (PBMCs) of three patients, two with a history of lymphoma and one with multiple sclerosis, a specific target site for latent integration of the full-length HHV-6 viral genome on the distal short arm of chromosome 17, in band p13.3. Fluorescence in situ hybridization (FISH) procedures were used to map more precisely the location of the viral integration site in one of those patients, relative to two known oncogenes mapped previously, namely CRK, and the more telomeric ABR oncogene. It is shown that the HHV-6 integration site is located at least 1,000 kb telomeric of ABR, and is very likely to map close to or within the telomeric sequences of 17p. This finding is significant given that human telomeric-like repeats flank the terminal ends of the HHV-6 genome. Cytogenetic studies showed evidence of karyotype instability in the peripheral blood cells infected latently.

The oncogenic 30 and 69 bp deletion variants of the EBV LMP-1 gene are common in HIV-negative lymphoproliferations, both malignant and benign

BACKGROUND

In vitro studies have shown that the 30 and 69 base pair (bp) deletion variants of the latent membrane protein (LMP)-1 gene of the Epstein-Barr virus (EBV) have a higher transforming capacity than the wild-type variant. In recent years these studies have triggered an in vivo search for such potentially oncogenic variants in lymphoid tissues.

PATIENTS AND METHODS

We used polymerase chain reaction (PCR) to investigate the prevalence of LMP-1 gene variants in EBV-positive lymph nodes from 60 HIV-negative Italian patients with benign and malignant lymphoid disorders.

RESULTS

The 30 bp variant was detected in 10 of 39 (25.6%) malignant lymphomas but also in 4 of 13 (30%) reactive lymphadenitis with follicular hyperplasia. Of note is the fact that the 69 bp variant was detected in three cases of malignant lymphoproliferation but also in two cases of localized Castleman's disease of hyalin vascular type.

CONCLUSIONS

The molecular detection of the oncogenic variants of the LMP-1 gene in a lymph node biopsy as an indicator of the aggressiveness of the EBV-associated lymphoproliferative disease must be considered with caution. The relatively high frequency of the 69 bp variant in our series compared with that reported in the literature probably reflects a different incidence of LMP-1 variants in healthy populations from different geographical areas.

Human herpesvirus 6 latently infects early bone marrow progenitors in vivo

We have studied the in vivo tropism of human herpesvirus 6 (HHV-6) for hemopoietic cells in patients with latent HHV-6 infection. Having used a variety of cell purification, molecular, cytogenetic, and immunocytochemical procedures, we report the first evidence that HHV-6 latently infects early bone marrow progenitor cells and that HHV-6 may be transmitted longitudinally to cells which differentiate along the committed pathways.

Cellular localization of human herpesvirus 8 in nonneoplastic lymphadenopathies and chronic interstitial pneumonitis by in situ polymerase chain reaction studies

OBJECTIVES

To study the cellular localization of human herpesvirus 8 (HHV-8) in rare cases of HHV-8 infection from Italy that are associated neither with human immunodeficiency virus (HIV) infection nor Kaposi's sarcoma (KS).

METHODS

The presence and distribution of HHV-8-infected cells was investigated by direct in situ polymerase chain reaction (PCR) in the lymph node tissues from 2 patients with reactive lymphadenopathies with florid follicular hyperplasia and increased vascularity and in the lung tissue from 1 patient with chronic interstitial pneumonitis.

RESULTS

HHV-8 was localized in lymphoid and monocyte-macrophage cells scattered in the interfollicular regions of both lymph nodes but not in endothelial cells. In the lung tissue, HHV-8 was found in the inflammatory cells infiltrating the interalveolar interstitium, in endothelial cells of the pulmonary vasculature, and in rare pneumocytes.

CONCLUSIONS

HHV-8 can infect nonneoplastic lymph nodes of immunocompetent subjects, and the distribution of infected cells outside of the germinal centers resembles that of Epstein-Barr virus (EBV)-infected cells in the lymph nodes in the course of infectious mononucleosis. Endothelial cells and pneumocytes may be a target of HHV-8 infection out of the KS setting, at least in the presence of a chronic inflammatory process.

Absence of a directly causative role for human herpesvirus 7 in human lymphoma and a review of human herpesvirus 6 in human malignancy

In search of a (new) viral etiological agent, we screened 64 lymph node samples from Hodgkin's disease (HD) and 43 samples (32 lymph node and 11 skin biopsies) from non-Hodgkin's lymphoma (NHL) for human herpesvirus 7 (HHV-7). Twenty-nine control samples were tested as well, including 17 with benign lymphadenopathy. None of the samples tested positive by Southern blot hybridization using HHV-7-specific probes. We conclude that there is no major HHV-7 load in human lymphoma and that HHV-7 is not likely to be directly involved in its etiology. This is in contrast to a small minority of human lymphoproliferative diseases in which HHV-6 can be found at high copy number, but in which an etiological role is still uncertain.

Expression of human herpesvirus-6 antigens in benign and malignant lymphoproliferative diseases

Immunohistochemistry was used to look for the expression of human herpesvirus-6 (HHV-6) antigens in a well characterized series of benign, atypical, and malignant lymphoid lesions, which tested positive for the presence of HHV-6 DNA. A panel of specific antibodies against HHV-6 antigens, characteristic either of the early (p41) or late (p101K, gp106, and gp116) phases of the viral cycle, was applied to the lymphoid tissues from 15 non-Hodgkin's lymphomas, 14 Hodgkin's disease cases, 5 angioimmunoblastic lymphadenopathies with dysproteinemia, 14 reactive lymphadenopathies, and 2 cases of sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease). In lymphomatous tissues, the expression of late antigens was documented only in reactive cells, and mainly in plasma cells. Of interest, the expression of the early p41 antigen was detected in the so-called "mummified" Reed-Sternberg cells, in two Hodgkin's disease cases. In reactive lymphadenopathies, the HHV-6 late antigen-expressing cells were plasma cells, histiocytes, and rare granulocytes distributed in interfollicular areas. In both cases of Rosai-Dorfman disease, the p101K showed an intense staining in follicular dendritic cells of germinal centers, whereas the gp106 exhibited an intense cytoplasmic reaction in the abnormal histiocytes, which represent the histological hallmark of the disease. The expression of HHV-6 antigens is tightly controlled in lymphoid tissues. The lack of HHV-6 antigen expression in neoplastic cells and the limited expression in degenerating Reed-Sternberg cells argue against a major pathogenetic role of the virus in human lymphomagenesis. The detection of a rather unique pattern of viral late antigen expression in Rosai-Dorfman disease suggests a possible pathogenetic involvement of HHV-6 in some cases of this rare lymphoproliferative disorder.

Clinico-pathological characterization of hepatitis C virus-related B-cell non-Hodgkin's lymphomas without symptomatic cryoglobulinemia

BACKGROUND

Epidemiological evidence has suggested an association between hepatitis C virus (HCV) infection and B-cell lymphoproliferation. We studied the prevalence of HCV infection in a series of de novo B-cell non-Hodgkin's lymphoma (B-NHL) cases and correlated virological findings with clinico-histological features.

PATIENTS AND METHODS

One hundred fifty-seven patients with de novo B-NHL were included in the study. Their serum was examined by ELISA and RIBA for the presence of anti-HCV antibodies, and either the peripheral blood mononuclear cells or the pathology tissues of all of the patients were examined by reverse transcriptase polymerase chain reaction for the presence of HCV RNA sequences.

RESULTS

HCV infection occurred in 22.3% of B-NHL patients and was documented before the diagnosis in about half of the positive cases. Of interest, HCV infection was more frequently found in follicular center, marginal zone and diffuse large-cell lymphoma types, but was not associated with symptomatic cryoglobulinemia. The median survival time was 48 months in HCV-positive and 52 months in HCV-negative B-NHL patients.

CONCLUSIONS

Our findings strengthen the pathogenetic link between HCV and B-NHL and show that HCV infection may be associated with the malignant proliferation of defined B-cell subsets other than the immunoglobulin Mk B-cell subset involved in the pathogenesis of mixed cryoglobulinemia type II and associated lymphoplasmacytoid lymphoma type. HCV-related liver disease did not affect the survival of our B-NHL patients.

Human herpesvirus-8 in hematological diseases

The huge amount of experimental and clinical observations supporting the possible involvement of human herpesvirus 8 (HHV-8) or Kaposi sarcoma herpesvirus (KSHV) in human lymphoproliferative diseases was critically reviewed during a workshop organized by the Italian Society for Experimental Hematology in Florence, Italy, on July 3rd, 1997. The organizers have prepared this report for the readers of Haematologica.

Alfa-interferon in the treatment of essential thrombocythemia: clinical results and evaluation of its biological effects on the hematopoietic neoplastic clone. Italian Cooperative Group on ET

The efficacy of alfa-interferon (alfa-IFN) in essential thrombocythemia (ET) patients has been reported by several authors. The aim of this study is to assess the magnitude of the effect of alfa-IFN on the neoplastic clone. As of December 1993, 11 ET patients received alfa-IFN at a dose of 3-6 MU/s.c./day for 6 months. Ten of 11 obtained complete hematological remission (CHR) and one achieved partial hematological remission. Megakaryocyte concentration was reduced in six cases. The spleen,which was enlarged in four patients, decreased in size in two patients. Seven of eight patients who were symptomatic at diagnosis obtained resolution of symptoms. In order to obtain indications about the structural modifications induced by alfa-IFN in ET megakaryocytes (Mks), Fourier-transform infra-red microspectroscopy analysis performed on 10 single Mks of each patient, was done in seven of 11 patients; the analysis showed a reduction of A1/A2 ratios (A1 integrated area of the band at 1080 cm(-1) due to the nucleic acids absorption; A2 integrated area of the band at 1540 cm(-1) due to proteic components absorption) in five cases, and in three of these five patients A1/A2 ratios achieved normal values. After alfa-IFN treatment we did not observe any change in the methylation pattern of DNA from the granulocyte fraction. Our results confirm the efficacy of alfa-IFN in ET patients, and the decrease of A1/A2 ratios in several patients is a demonstration of the depth of the effect of alfa-IFN on the neoplastic clone. The results of clonality studies showed the persistence of clonal hematopoiesis. Whether higher alfa-IFN dose and/or more prolonged alfa-IFN therapy may allow a restoration of polyclonal hematopoiesis remains to be determined and should be explored in future clinical trials.

Chronic myeloid leukemia with thrombocythemic onset may be associated with different BCR/ABL variant transcripts

Ph-positive chronic myeloid leukemia (CML) mimicking essential thrombocythemia (ET) at onset seems to be a distinct clinical entity. Whether this rare clinical form of CML is associated with single, specific variants of BCR/ABL transcripts is a matter of debate. Among 82 consecutive patients with Ph-positive CML, we identified 3 patients in which the disease mimicked ET at presentation, because of marked thrombocytosis and moderate leukocytosis, with few immature myeloid cells in peripheral blood and blood basophilia in 2 of them. Molecular analysis with the reverse transcriptase-polymerase chain reaction technique showed the presence of b2a2, b3a2, and b3a2-b2a2 transcript variants in the three patients, respectively. The results of our study together with a review of literature data suggest that different BCR/ABL transcript variants may occur in CML mimicking ET, without an apparently significant prevalence of one type.

Occurrence of a novel t(11;19)(q13;q13.3) in complete remission of acute promyelocytic leukemia

A woman with t(15;17) and PML/RAR alpha positive acute promyelocytic leukemia (APL-M3v) achieved a complete remission (CR) with cytogenetic and molecular conversion, after one-month ATRA plus idarubicin treatment. During CR, less than one-month after consolidation therapy with topoisomerase II inhibitors, a novel t(11;19) (q13;q13.3) was detected in peripheral blood stem cells and later in harvest bone marrow cells. Persisting CR and the negativity for BCL1 and PRAD1 genes rearrangement, the autotransplantation was performed, with good outcome. The patient is still in CR eighteen months post-transplant, in spite of the persistence of a small t(11;19) clone in BM cells. The emergence of a novel chromosomal change during CR of acute leukemia is a rare phenomenon. This is the first t(11;19)(q13;q13.3) described in APL. This finding raises the issue of whether the abnormal karyotypes at remission might represent a risk of tumor recurrence. The meaning of this genomic instability is yet unknown.

L-arginine infusion decreases platelet aggregation through an intraplatelet nitric oxide release

Nitric Oxide (NO) inhibits platelet aggregation via activation of an intraplatelet soluble guanylate cyclase which induces an increase in cyclic GMP (1). It has been also demonstrated that platelets contain a constitutive, calcium-dependent, NO synthase which is activated by collagen-induced platelet aggregation. This leads to a NO synthesis from L-Arginine (L-Arg), which in turn increases cyclic GMP and down-regulates platelet aggregation (2). In vitro administration of supraphysiological concentrations of L-Arg enhances platelet cyclic GMP levels by increasing NO production and reduces platelet aggregation. This effect is reversed by pre-incubation with NO-synthase inhibitors (3). These results indicate that the L-Arg: NO pathway plays an important role in the modulation of human platelet aggregation (4). In vivo L-Arg, when administered i.v., induces hypotension (5) and vasodilatation (6,7) in humans, and when orally supplemented reduces platelet aggregability both in hypercholesterolemic rabbits and healthy men (8,9).

Hepatitis C virus-induced leuko-thrombocytopenia and haemolysis

Hepatitis C virus (HCV) has been recognized as the cause of thrombocytopenia occurring in patients with chronic hepatitis C, possibly through autoimmune mechanisms. A patient is described with B cell chronic lymphocytic leukaemia, presenting with a marked leuko-thrombocytopenia and an associated mild haemolysis secondary to HCV infection, in the absence of clinical and biochemical signs of hepatitis. Anti-HCV antibodies were detected in the serum both by ELISA and RIBA but not 2 months before the onset of cytopenia. The presence of HCV RNA was documented both in the peripheral blood mononuclear cells and in the bone marrow by reverse transcriptase polymerase chain reaction of the 5' untranslated region of the viral genome. Of interest, HCV RNA was also found in the serum, showing that viraemia was associated with the presence of circulating anti-HCV antibodies. HCV genotyping, performed by PCR amplification of the core region, revealed the presence of an unclassifiable genotype. The hypothetical mechanisms leading to HCV-induced cytopenia in this patient are briefly discussed. Treatment with corticosteroids was effective in controlling blood cell counts, without increasing viraemia and deterioration of liver disease. HCV infection should be considered in the differential diagnosis of possible causes of cytopenia, mainly in immunosuppressed patients, even in absence of clinical and biochemical signs of hepatitis.

Human herpesvirus-6 reactivation in a longitudinal study of two HIV-1 infected patients

After primary infection, human herpesvirus-6 (HHV-6) persists in latent form and can be reactivated in immunocompromised subjects. A longitudinal study of HHV-6 infection was carried out in two HIV-1 seropositive patients to provide in vivo evidence of HHV-6 reactivation. Concomitant with a significant rise of anti-HHV-6 IgG detected by IFA, a transient increase of HHV-6 viral load was shown in PBLs by PCR. During HHV-6 reactivation it was also identified either cell-free HHV-6 by PCR in plasma or IgM antibody titers. HHV-6 reactivation was followed by a temporary decrease in CD4+ count and by a progressive dramatic loss of CD4+ during the following 18 months. HHV-6 strain characterization by PCR demonstrated that first patient (MM) initially showed the B variant, followed by reactivation and persistence of the A variant, while in the second (SG) only the A variant was detected. The evidence of HHV-6 reactivation suggests its involvement in immunologic damage underlying the disease.