HHV-8 Is Present in Multiple Myeloma Patients

Polyclonal serum free light chain elevation is associated with increased risk of monoclonal gammopathies

Monoclonal gammopathies (MG) constitute a spectrum of disorders starting from a monoclonal gammopathy of undetermined significance (MGUS) to active disease requiring therapy such as multiple myeloma. MG are characterized by proliferation of clonal plasma cells (PC) secreting a monoclonal protein either as intact immunoglobulin or free kappa or lambda free light chains (FLC). We hypothesized that a polyclonal elevation of serum FLC may indicate an inflammatory state that precedes development of MG. We studied 15,630 individuals from Olmsted county, who did not have MGUS based on baseline screening studies. At a median follow-up of 18.1 years, 264 patients had developed a clonal PC disorder; 252 with MGUS, 1 with SMM, 8 with MM, and 3 with amyloidosis, translating to an annual incidence of development of a MG of 0.1%. We examined the baseline polyclonal ΣFLC (kappa + lambda FLC) from the initial screening and grouped them into deciles. The highest decile group had a 2.6-fold (95% CI; 1.8, 3.7) increase in the risk of developing a MG, P < 0.001. We demonstrate for the first time, the increased risk of developing MG in patients with elevated serum FLC, suggesting that an underlying inflammatory state may play an etiologic role.

Effects of Epstein-Barr virus infection on the development of multiple myeloma after liver transplantation

Reduced cellular immune function in patients after liver transplantation easily results in many types of viral infections, such as Epstein-Barr virus. Epstein-Barr virus is a Γ-herpesvirus and is related to many malignant diseases, especially epithelial and lymph tumors. The abnormal interaction of cluster of differentiation 40 with cluster of differentiation 40 ligand and expression of cluster of differentiation 40 ligand are considered closely related to the development of myeloma cells. This study explored the influence and mechanism of Epstein-Barr virus infection on the phenotype and biological behavior of myeloma cells after liver transplantation. Flow cytometry was used to detect coexpression of cluster of differentiation 40 and cluster of differentiation 40 ligand in 10 samples of freshly isolated multiple myeloma cells. Cluster of differentiation 40 and cluster of differentiation 40 ligand were coexpressed in sample Nos. 5, 8, 9, and 10, particularly in sample No. 5. Western blot analysis was used to detect the expression of the Epstein-Barr virus antigens latent membrane protein 1 and Epstein-Barr virus nuclear antigen 2 in the multiple myeloma cell line RPMI 8226 infected with Epstein-Barr virus. The antigen expression indicated that Epstein-Barr virus can infect multiple myeloma virus cells in vitro. Reverse transcription-polymerase chain reaction revealed upregulated expression of cluster of differentiation 40 ligand on the infected RPMI 8226 cells, which may be involved in the anti-apoptosis activity of the infected cells. Confocal microscopy showed that pairs of molecules of cluster of differentiation 40, cluster of differentiation 40 ligand, and latent membrane protein 1 were colocalized on the surface of the infected cells. CXC chemokine receptor 4 was upregulated on the RPMI 8226 cells after Epstein-Barr virus infection. The migratory ability of the infected cells improved in the presence of the chemokine stromal cell-derived factor-1α. Anti-apoptosis and migration are known important biological characteristics of malignant cells. Our results indicate the involvement of Epstein-Barr virus in the origin and development of multiple myeloma. The risk of multiple myeloma increases when Epstein-Barr virus infects B cells in the germinal center, which may result in an anti-apoptosis effect of B cells and an improved ability to migrate from the germinal center to peripheral blood.

Reflections on the interpretation of heterogeneity and strain differences based on very limited PCR sequence data from Kaposi's sarcoma-associated herpesvirus genomes

Ever since the original identification of fragments of KSHV DNA in Kaposi's sarcoma (KS) tissue by Chang et al. in 1994, PCR has been used successfully and extensively to detect the virus in clinical samples from the accepted etiological diseases of KS, PEL and MCD. However, a number of other clinical and epidemiological studies claiming evidence for KSHV in multiple myeloma or sarcoid and more recently in primary pulmonary hypertension, as well as claims about the biological significance of DNA sequence polymorphisms based just on small ORF26 PCR DNA fragments have not been convincing. Here, we evaluate the validity and interpretations of previous results in the context of both the observed rates and global patterns of sequence variability within an extended ORF26 locus, as well as from the perspective of the overall levels of KSHV variability found after sampling multiple loci across the complete KSHV genome. The results cast doubts on most claims for biological significance for these polymorphisms, which instead correlate with viral subtype clustering arising from geographic and ethnic divergence of the ancestral human hosts. In addition, we describe several observations that help to explain likely sources of the often either unexpectedly high or unexpectedly low levels of sporadic variability seen in the PCR DNA sequence data reported in some of those studies.

Number of siblings and the risk of lymphoma, leukemia, and myeloma by histopathology

Epidemiologic evidence indicates that several markers of exposure to childhood infections are inversely associated with the risk of childhood leukemia and lymphomas. We used the Swedish Family-Cancer Database to assess the effects of number of siblings on the risk of non-Hodgkin's (n = 7,007) and Hodgkin's lymphomas (n = 3,115), leukemias (n = 7,650), and multiple myeloma (n = 1,492) by histopathology. Poisson regression models included terms for age, sex, family history, period, and socioeconomic index. Having four or more siblings compared with none was associated with an excess risk of childhood acute lymphoblastic leukemia [ALL; rate ratio (RR), 2.11; P(trend) = 0.001], acute monocytic leukemia (RR, 2.51; P(trend) = 0.002), and multiple myeloma (RR, 1.34; P(trend) = 0.006). Having three or more older siblings compared with none decreased the risk of acute monocytic leukemia (RR, 0.35; P(trend) = 0.001) and childhood ALL (RR, 0.69; P(trend) = 0.01). The risk of Hodgkin's lymphoma for five or more older siblings compared with none was 0.41 (P(trend) = 0.003). Acute myeloid leukemia, chronic lymphocytic leukemia, and other lymphoproliferative malignancies were not associated with number of siblings. In conclusion, we found an excess risk of childhood ALL and acute monocytic leukemia in large families. However, for ALL, acute monocytic leukemia, and Hodgkin's lymphoma, younger siblings were strongly protected compared with older siblings. The remarkable protective effect of number of older siblings on acute monocytic leukemia is a novel finding of potential interest. Possible interpretations of our findings in the context of a putative infectious etiology are discussed.

Interleukin-6 and its receptor: from bench to bedside

Interleukin-6 (IL-6) is an inflammatory cytokine with a well-documented role in inflammation and cancer. The cytokine binds to a membrane bound IL-6 receptor (IL-6R) and this complex associates with two molecules of the signal transducing protein gp130 thereby initiating intracellular signaling. While gp130 is present on most if not all cells of the body, the IL-6R is only present on some cells, mainly hepatocytes and several leukocytes. Cells, which only express gp130 and no IL-6R are refractory to IL-6 signals. We have shown earlier that the IL-6R can exist as a soluble protein generated by limited proteolysis of the membrane bound receptor or by translation from an alternatively spliced mRNA. This soluble IL-6R (sIL-6R) can bind the ligand IL-6 and the soluble complex of sIL-6R and IL-6 can bind to gp130 on cells which lack the membrane bound IL-6R and trigger gp130 signaling. We have named this process 'trans-signaling'. We will review data, which clearly show that IL-6 uses classical signaling via the membrane bound receptor and trans-signaling via the soluble receptor in various physiological and pathophysiological situations. Furthermore, we have developed designer cytokines, which can specifically enhance or inhibit IL-6 trans-signaling. These designer cytokines have been shown to be extremely useful to in therapeutic applications ranging from the long-term culture of stem cells and enhancing liver regeneration up to the blockade of chronic inflammation and cancer.

Cytokines and signal transduction

Many studies have characterized the role of growth factors in multiple myeloma (MM) pathogenesis and have derived novel therapies to improve patient outcome based upon targeting cytokines and their signaling cascades both in the MM cell and in the bone-marrow (BM) microenvironment. These cytokines include interleukin 6 (IL-6), insulin-like growth factor 1 (IGF-1), vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), stromal cell-derived factor 1alpha (SDF-1alpha), IL-21, B-cell stimulating factor 3 (BSF-3) and fibroblast growth factor (FGF). These cytokines are secreted from stromal cells (SCs), endothelial cells and/or osteoclasts, and promote MM cell growth, survival and migration, as well as paracrine cytokine secretion and angiogenesis in the BM milieu. Thus inhibition of signaling cascades induced by these cytokine provides rationale for a therapeutic option for MM.

Kaposi's sarcoma-associated herpesvirus: clinical, diagnostic, and epidemiological aspects

Kaposi's sarcoma-associated herpesvirus (KSHI) is one of the few viruses proven to be associated with tumorigenesis in humans. Its causal association with all clinical and epidemiological variants of Kaposi's sarcoma (KS) is well established. KSHV is also involved in the pathogenesis of primary effusion lymphoma (PEL) and a subset of multicentric Castleman's disease (MCD). Possible associations of KSHV with other clinical settings have been extensively examined. The findings from several of these studies are contradictory and are yet to be resolved. Concentrated effort over the last decade, since the initial discovery of KSHV, led to the development of several experimental systems that resulted in a better comprehension of the biological characteristics of KSHV and set the stage for the understanding of mechainisms by which diseases are induced by the virus. The development of molecular, histological, and serological tools for KSHV diagnosis allowed researchers to track the transmission and to study the epidemiology of KSHV. These assays have been applied, in particular in ambiguous cases, in order to confirm clinically and pathologically based diagnoses. Here, we review the advances in the clinical, experimental, diagnostic, and epidemiological research of KSHV.

Kaposi sarcoma-associated herpesvirus and primary and secondary pulmonary hypertension

BACKGROUND

Kaposi sarcoma-associated herpesvirus (KSHV) has been implicated as a factor in the pathogenesis of primary pulmonary hypertension (PPH). We conducted a case-control study of patients with PPH and pulmonary hypertension (PH) associated with other disorders (secondary PH) to look for evidence of KSHV infection.

MATERIALS AND METHODS

The study population was composed of patients with a diagnosis of PH at the University of California San Francisco Medical Center Department of Cardiology between July and November 2003. Serologic testing for KSHV was performed using enzyme-linked immunosorbent assays based on peptides from open reading frame-65 and K8.1, using sera from 19 patients with PPH, 29 patients with secondary PH, and 150 control subjects

RESULTS

The overall seroprevalence of KSHV among all study participants was 2.0%. The rate among control subjects was 0.7% (1 of 150 subjects); among the study participants with PPH, we found no evidence of KSHV infection (0 of 19 patients). There was no significant difference between the observed seroprevalence of KSHV among patients with PPH compared to control subjects (p = 0.89). Of the 29 patients with a diagnosis of secondary PH, 3 patients (10.3%) were KSHV seropositive. Significantly, two of the three KSHV-infected secondary PH patients were also HIV positive, a known independent risk factor for KSHV infection and secondary PH.

CONCLUSION

Our data do not support KSHV infection having a significant role in PPH or non-HIV-associated secondary PH compared to age- and gender-matched control subjects.

New developments in IL-6 dependent biology and therapy: where do we stand and what are the options?

Interleukin-6 (IL-6) is a four-helical protein which, on target cells, binds to a specific IL-6-receptor and two molecules of the promiscuous signal transducing protein gp130. Structure-function analysis defined three molecular contact sites between IL-6 and its receptor subunits. Using this information, competitive antagonistic proteins as well as hyperagonistic proteins were developed. Possible therapeutic applications of IL-6 antagonists are in IL-6 dependent haematological disorders (Castleman's disease, POEMS syndrome, multiple myeloma) and bone diseases (Paget's disease, osteoporosis). Designer IL-6 antagonists could suppress inflammatory activity in rheumatic and autoimmune diseases and could prevent secondary amyloidosis. IL-6 antagonists could also prove advantageous in myocardial infarction and unstable angina pectoris. IL-6 antagonists might slow down development of (mesangioproliferative) glomerulonephritis. On the other hand, hyperagonistic variants of IL-6 have a potential in ex vivo expansion of bone marrow stem cells and as thrombopoietic agents. They might also be developed into drugs to support liver regeneration in vivo and to treat stress-induced cardiac insufficiency.

Increased seroprevalence of human herpesvirus 8 in patients with hematological disorders

Human herpesvirus 8 (HHV8) has been consistently linked to Kaposi's sarcoma and many hematological diseases such as pleural effusion lymphoma, multicentric Castleman's disease, some lymphoproliferative diseases and posttransplantation bone marrow failure. However, whether patients with hematological disorders are at a higher risk of HHV8 infection has not been determined. In this study, indirect immunofluorescence was used to detect antibodies against lytic antigens of HHV8 in 265 patients with hematological disorders. Our data showed that 24.5% of patients (65/265) were seropositive for HHV8 IgG antibody, which was significantly higher than in our general population (p < 0.001). A significantly higher seropositive rate can be found in patients with lymphoma, leukemia, autoimmune cytopenias and myeloproliferative disorders, but not in patients with myeloma or aplastic anemia. No difference in the seropositive rate is associated with gender or age. We conclude that some patients with hematological disorders are at a higher risk of HHV8 infection.

Molecular genetics of Kaposi's sarcoma-associated herpesvirus (human herpesvirus-8) epidemiology and pathogenesis

Kaposi's sarcoma had been recognized as unique human cancer for a century before it manifested as an AIDS-defining illness with a suspected infectious etiology. The discovery of Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, in 1994 by using representational difference analysis, a subtractive method previously employed for cloning differences in human genomic DNA, was a fitting harbinger for the powerful bioinformatic approaches since employed to understand its pathogenesis in KS. Indeed, the discovery of KSHV was rapidly followed by publication of its complete sequence, which revealed that the virus had coopted a wide armamentarium of human genes; in the short time since then, the functions of many of these viral gene variants in cell growth control, signaling apoptosis, angiogenesis, and immunomodulation have been characterized. This critical literature review explores the pathogenic potential of these genes within the framework of current knowledge of the basic herpesvirology of KSHV, including the relationships between viral genotypic variation and the four clinicoepidemiologic forms of Kaposi's sarcoma, current viral detection methods and their utility, primary infection by KSHV, tissue culture and animal models of latent- and lytic-cycle gene expression and pathogenesis, and viral reactivation from latency. Recent advances in models of de novo endothelial infection, microarray analyses of the host response to infection, receptor identification, and cloning of full-length, infectious KSHV genomic DNA promise to reveal key molecular mechanisms of the candidate pathogeneic genes when expressed in the context of viral infection.

Laboratory diagnosis of human herpesvirus 8 infection in humans

Human herpesvirus 8 (HHV-8) is causally associated with Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman's disease. Serological and molecular biology assays are used to investigate the biology of this virus in different populations and diseases. Serological assays are mainly used to study the prevalence of the viral infection and to predict the diagnosis of Kaposi's sarcoma and other HHV-8-associated cancers. The appearance of antibodies against lytic antigens precedes the appearance of antibodies against latent antigens, probably explaining the lower sensitivity of assays based on latent HHV-8 antigens. The lack of international reference serum panels is presently the major bottleneck for further progress in the field of HHV-8 serology. Molecular biological assays are an absolute requirement for both the diagnosis and the follow-up of HHV-8 infection. Qualitative methods have been particularly useful to elucidate the mode of transmission and the causal association between HHV-8 and HHV-8-associated diseases. Quantitative methods have become an essential tool to monitor the progression of the infection and the effects of antiviral therapies. This review analyzes the performance of the different serological and molecular biological assays available at present. The main conclusion is that more research is needed to define the most useful laboratory tests for the diagnosis of HHV-8 infection and to establish the clinical role of such tests.

Spectrum of Kaposi's sarcoma-associated herpesvirus, or human herpesvirus 8, diseases

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), discovered in 1994, is a human rhadinovirus (gamma-2 herpesvirus). Unlike other human herpesviruses (herpes simplex virus, Epstein-Barr virus, varicella-zoster virus, cytomegalovirus, HHV-6, and HHV-7), it is not widespread in the general population and has many unique proteins. HHV-8 is strongly associated with all subtypes of Kaposi's sarcoma (KS), multicentric Castleman's disease, and a rare form of B-cell lymphoma, primary effusion lymphoma. In addition, HHV-8 DNA sequences have been found in association with other diseases, but the role of the virus in these diseases is largely unconfirmed and remains controversial. The seroprevalence of HHV-8, based on detection of latent and lytic proteins, is 2 to 5% in healthy donors except in certain geographic areas where the virus is endemic, 80 to 95% in classic KS patients, and 40 to 50% in HIV-1 patients without KS. This virus can be transmitted both sexually and through body fluids (e.g., saliva and blood). HHV-8 is a transforming virus, as evidenced by its presence in human malignancies, by the in vitro transforming properties of several of its viral genes, and by its ability to transform some primary cells in culture. It is not, however, sufficient for transformation, and other cofactors such as immunosuppressive cytokines are involved in the development of HHV-8-associated malignancies. In this article, we review the biology, molecular virology, epidemiology, transmission, detection methods, pathogenesis, and antiviral therapy of this newly discovered human herpesvirus.

Cancers associated with Kaposi's sarcoma (KS) in AIDS: a link between KS herpesvirus and immunoblastic lymphoma

Kaposi's sarcoma (KS), common among persons with acquired immunodeficiency syndrome (AIDS), is caused by KS herpesvirus (KSHV) but whether KSHV causes other malignancies is uncertain. Using linked United States AIDS and cancer registries, we measured the incidence of specific malignancies in persons with AIDS (4-27 months after AIDS onset). We identified associations with KSHV by calculating a relative risk: cancer incidence in persons with KS (all were KSHV-infected) divided by incidence in persons without KS. Using Poisson regression, relative risks were adjusted for human immunodeficiency virus risk group, gender, age, race, and calendar year. We included 189 159 subjects (26 972 with KS). Immunoblastic lymphoma was significantly associated with KS (506 cases; relative risks: unadjusted 2.44, 95%CI 2.00-2.96, adjusted 1.58, 95%CI 1.29-1.93). Only one immunoblastic lymphoma had pleura as primary site. None of 37 other specified malignancies (other non-Hodgkin lymphomas, haematological malignancies, solid tumours) was significantly associated with KS. In summary, the association of immunoblastic lymphoma with KS was specific among examined malignancies and remained significant after statistical adjustment. Our findings, and the previously demonstrated presence of KSHV in the histologically related primary effusion lymphoma, suggest that KSHV is involved in the pathogenesis of some immunoblastic lymphomas.

Frequent demonstration of human herpesvirus 8 (HHV-8) in bone marrow biopsy samples from Turkish patients with multiple myeloma (MM)

In order to investigate the frequency of HHV-8 in MM patients from another geographic location, we obtained fresh bone marrow (BM) biopsies from Turkish patients with MM (n = 21), monoclonal gammopathy of undetermined significance (MGUS) (n = 2), plasmacytoma (n = 1) with BM plasma cell infiltration, various hematological disorders (n = 6), and five healthy Turkish controls. The frequency of HHV-8 was analyzed by polymerase chain reaction (PCR) in two independent laboratories in the USA and in Turkey. Using fresh BM biopsies, 17/21 MM patients were positive for HHV-8 whereas all five healthy controls, and six patients with other hematological disorders were negative. Two patients with MGUS, and one patient with a solitary plasmacytoma were also negative. The data from the two laboratories were completely concordant. Also using primer pairs for v IRF and v IL-8R confirmed the results observed with the KS330233 primers. Furthermore, sequence analysis demonstrated a C3 strain pattern in the ORF26 region which was also found in MM patients from the US. Thus, HHV-8 is present in the majority of Turkish MM patients, and the absence of the virus in healthy controls further supports its role in the pathogenesis of MM.

Detection of Kaposi sarcoma-associated herpesvirus in bone marrow biopsy samples from patients with multiple myeloma

BACKGROUND

Kaposi sarcoma-associated herpesvirus (KSHV) recently has been identified in the bone marrow (BM) dendritic cell of multiple myeloma (MM) patients. However, whether or not KSHV is associated with MM remains controversial because many studies have failed to detect the presence of KSHV DNA sequences in the BM of their MM patients.

METHODS

We have assayed for KSHV DNA sequences in the BM biopsy samples from 49 patients with MM and from 8 patients with normal BM, using nested polymerase chain reaction and dot blot analysis. The polymerase chain reaction product of KSHV was further determined by single-strand conformation polymorphism and sequence analyses.

RESULTS

KSHV DNA was detectable in 22 of 49 patients (44.9%) with MM but was not detectable in normal BM cells. Single-strand conformation polymorphism and sequence analyses showed that there were interpatient specific mutations. Sixteen out of 22 KSHV DNA sequences belonged to a previously defined subgroup, and the other 6 remain unclassified and may represent distinct strains of KSHV in Taiwan.

CONCLUSIONS

Data strongly supported that KSHV infection did exist in the BM of the current study patients with MM. However, the role of KSHV in the pathogenesis of multiple myeloma remains to be determined.

Biological features of the clone involved in primary amyloidosis (AL)

Primary light chain-associated amyloidosis (AL) is a plasma cell dyscrasia that causes morbidity via systemic tissue deposition of monoclonal light chains in the form of fibrils (amyloid). It is the most common form of systemic amyloidosis in Western countries and is rapidly fatal. Knowledge of the pathobiology of the underlying B cell clone is of primary importance for the design and optimization of therapeutic strategies.

Polymerase chain reaction detection of Kaposi's sarcoma-associated herpesvirus-optimized protocols and their application to myeloma

Since its discovery in 1994, KSHV (also called human herpesvirus-8 or HHV8) has been implicated in a variety of disorders. Although the association of KSHV with Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease has been well established, its presence in some other diseases, such as multiple myeloma, remains controversial. Because most KSHV studies are based on polymerase chain reaction (PCR) analysis, the conflicting data may be attributable to variations in the methods, primer sets, and target sequences selected. To establish an efficient and reliable PCR approach for KSHV detection we designed eight sets of primers to six regions (ORFK1, ORFK2, ORFK9, ORK26, ORF72, and ORF74) of the KSHV genome using appropriate database and software. The detection sensitivity of these primers was carefully assessed and their reliability was strictly validated in a series of positive (15 KS and PEL samples) and negative (16 lymphoid tissues) controls. We found that primer sets to the ORFK9 region showed the highest sensitivity, whereas primer sets to ORFK1 and ORF74 showed the lowest sensitivity. Primer sets to ORFK9, ORF26 and ORF72 regions detected all of the positive cases, whereas other primer sets showed varying detection rates or nonspecific bands. All 16 negative controls were negative with all primer sets. However, six of 16 negative controls became positive when we used nested PCR targeting ORF26. Therefore, multiple target KSHV sequences increase the detection efficiency, while nested PCR protocols are likely to introduce false positivity. Using ORFK9, ORF26 and ORF72 primer sets, we screened bone marrow biopsies from 18 cases of multiple myeloma, and failed to detect any KSHV sequences. This finding supports the conclusion that KSHV is not associated with multiple myeloma. Indeed, our results further confirm that although KSHV is universally present in Kaposi's sarcoma and primary effusion lymphoma, it is not ubiquitious.

A negative search for a paramyxoviral etiology of Paget's disease of bone: molecular, immunological, and ultrastructural studies in UK patients

Paget's disease of bone is a common bone disease characterized by increased and disorganized bone remodeling at focal sites throughout the skeleton. The etiology of the disease is unresolved. A persistent viral infection has long been suggested to cause the disease. Antigen and/or nucleic acid sequences of paramyxoviruses (in particular measles virus [MV], canine distemper virus [CDV], and respiratory syncytial virus [RSV]) have been reported in pagetic bone by a number of groups; however, others have been unable to confirm this and so far no virus has been isolated from patients. Here, we reexamined the question of viral involvement in Paget's disease in a study involving 53 patients with established disease recruited from seven centers throughout the United Kingdom. Thirty-seven patients showed clear signs of active disease by bone scan and/or histological assessment of the bone biopsy specimens and 12 of these had not received any therapy before samples were taken. Presence of paramyxovirus nucleic acid sequences was sought in bone biopsy specimens, bone marrow, or peripheral blood mononuclear cells using reverse-transcription polymerase chain reaction (RT-PCR) with a total of 18 primer sets (7 of which were nested), including 10 primer sets (including 3 nested sets) specifically for MV or CDV. For each patient at least one sample was tested with all primer sets by RT-PCR and no evidence for the presence of paramyxovirus RNA was found in any patient. In 6 patients, bone biopsy specimens with clear histological evidence of active disease tested negative for presence of measles and CDV using immunocytochemistry (ICC) and in situ hybridization (ISH). Intranuclear inclusion bodies, similar to those described by others previously, were seen in pagetic osteoclasts. The pagetic inclusions were straight, smooth tubular structures packed tightly in parallel bundles and differed from nuclear inclusions, known to represent MV nucleocapsids, in a patient with subacute sclerosing panencephalitis (SSPE) in which undulating, diffuse structures were found, arranged loosely in a nonparallel fashion. In the absence of amplification of viral sequences from tissues that contain frequent nuclear inclusions and given that identical inclusions are found in other bone diseases with a proven genetic, rather than environmental, etiology, it is doubtful whether the inclusions in pagetic osteoclasts indeed represent viral nucleocapsids. Our findings in this large group of patients recruited from throughout the United Kingdom do not support a role for paramyxovirus in the etiology of Paget's disease.

CD68+/CD83+/CD1a- dendritic cell subsets from patients with multiple myeloma are not infected with human herpesvirus 8

Recently, a subset of dendritic cells with the phenotype CD68+/CD83+/CD1a-, present in patients with multiple myeloma (MM), was reported to be infected with human herpesvirus 8 (HHV-8). Therefore we wished to clarify whether HHV-8 infection might be related to the pathogenesis of MM. In an attempt to identify HHV-8 infected cells in patients with MM, long-term bone marrow cultures from 8 MM patients and dendritic cell cultures from 11 MM patients were established. In addition, fresh bone marrow aspirates from 10 MM and 10 patients with monoclonal gammopathy of undetermined significance (MGUS) were included in the study. All samples were analysed by a sensitive semi-nested PCR assay and were found to be consistently PCR negative. Phenotyping of day 7 dendritic cell cultures demonstrated the presence of a sufficient number of CD68+/CD1a- and CD83+/CD1a- cells. However, to exclude the presence of infrequent HHV-8 infected cells, the CD68+/CD1a- subset from 3 dendritic cell cultures was sorted in numbers of 105 for each PCR test, and again a negative PCR result was observed. This study documents that the CD68+/CD83+/CD1a- dendritic cells in patients with MM are not generally infected with HHV-8 and, as a consequence, it is unlikely that HHV-8 plays a role in the pathogenesis of MM.

Kaposi's sarcoma-associated herpesvirus gene sequences are detectable at low copy number in primary amyloidosis

Primary amyloidosis (AL), like multiple myeloma (MM), results from a clonal proliferation of plasma cells. Recent detection of Kaposi's sarcoma-associated herpesvirus (KSHV) gene sequences in MM patients, although controversial, suggested that KSHV may also be present in AL. In the present study, we assayed for KSHV gene sequences in patients with primary AL independently in 2 laboratories. Nested polymerase chain reaction (PCR) was performed on DNA isolated from 21 bone marrow (BM) core biopsy samples to amplify orf26 and orf72, 2 regions of the KSHV genome. Eighteen of 21 (86%) BM core biopsy samples were KSHV PCR positive. BM aspirates from 16 of these 21 AL patients were cultured for 4-6 weeks to generate long term bone marrow stromal cells (LT-BMSCs), and 13 of 16 (81%) LT-BMSCs were also KSHV PCR positive. Results in all but 1 sample were consistent in the 2 laboratories. Sequencing of the PCR products in the 2 laboratories confirmed 94-98% and 95-98% homology to the published orf 26 and orf 72 KSHV gene sequences respectively, with interpatient base pair differences. Despite the presence of KSHV gene sequences, only 4/18 (22%) KSHV PCR positive patients demonstrated KSHV lytic antibodies by immunoblot assay. A sensitive assay performed on the BCBL-1 cell line confirmed the presence of KSHV at a very low copy number in AL. PCR using patient specific light chain gene primers also amplified DNA isolated from 2 AL BM core biopsies and 3 AL LT-BMSCs which were KSHV PCR positive, suggesting the presence of clonotypic cells. Our results therefore demonstrate KSHV gene sequences albeit at a very low copy number in the majority of BM core biopsies and LT-BMSCs from AL patients, and serological responses in only a minority of cases. Ongoing studies to identify viral transcripts and gene products will determine the biological relevance of KSHV in AL disease pathogenesis.

Human herpes virus 8 interleukin-6 homologue triggers gp130 on neuronal and hematopoietic cells

Human herpes virus-8 (HHV8) encodes a cytokine named viral interleukin-6 (vIL-6) that shares 25% amino-acid identity with its human homologue. Human IL-6 is known to be a growth and differentiation factor of lymphatic cells and plays a potential role in the pathophysiology of various lymphoproliferative diseases. vIL-6 is expressed in HHV8-associated-diseases including Kaposi's sarcoma, Body-cavity-based-lymphoma and Castleman's disease, suggesting a pathogenetic involvement in the malignant growth of B-cell associated diseases and other malignant tumours. We expressed vIL-6 in Escherichia coli as a fusion protein with recombinant periplasmic maltose binding protein. After cleavage from the maltose binding protein moiety and purification, vIL-6 was shown to be correctly folded using circular dichroism spectroscopy. A rabbit antiserum was raised against the recombinant vIL-6 protein. vIL-6 turned out to be active on cells that expressed gp130 but no IL-6 receptor (IL-6-R) suggesting that, in contrast to human IL-6, vIL-6 stimulated gp130 directly. Accordingly, vIL-6 activity could be inhibited by a soluble gp130 Fc Fusion protein. vIL-6 was shown to induce neuronal differentiation of rat pheochromocytoma cells and to stimulate colony formation of human hematopoietic progenitor cells. Thus, vIL-6 exhibits biologic activity that has only been observed for the IL-6/soluble IL-6-R complex but not for IL-6 alone. These properties are important for the evaluation of the pathophysiological potential of vIL-6.

Absence of herpesvirus DNA sequences in the 5T murine model of human multiple myeloma

Kaposi's sarcoma-associated herpesvirus (KSHV, also known as HHV-8) has been found in patients with multiple myeloma (MM) and postulated to be aetiologically associated with the development of this common plasma cell malignancy. A murine model of MM was previously established in which intravenous transfer of 5T myeloma cells into C57BL/KaLwRij mice resulted in characteristic features of human MM. In the present study, we sought to identify herpesvirus DNA sequences in this murine model of MM through polymerase chain reaction (PCR) analysis using primers specific for KSHV, murine herpesvirus 68 (MHV68) and murine cytomegalovirus (MCMV) as well as consensus primers designed from the highly conserved DNA polymerase genes of the Herpesviridae family. None of the DNA samples from whole bone marrow (n = 6) or dendritic cells enriched by long-term culture (n = 8) of 5T myeloma-bearing mice as well as the 5T myeloma cell lines (n = 3) maintained in long-term culture yielded specific amplification products in any of the PCR assays. Two KSHV-specific serological assays measuring antibodies to KSHV latent and lytic antigens also failed to detect the presence of anti-KSHV antibodies in mice that developed MM. These results suggest that the development of 5T murine MM is unlikely to be involved with KSHV or a KSHV-like murine herpesvirus.

IL-6 receptor independent stimulation of human gp130 by viral IL-6

The genome of human herpes virus 8, which is associated with Kaposi's sarcoma, encodes proteins with similarities to cytokines and chemokines including a homologue of IL-6. Although the function of these viral proteins is unclear, they might have the potential to modulate the immune system. For viral IL-6 (vIL-6), it has been demonstrated that it stimulates IL-6-dependent cells, indicating that the IL-6R system is used. IL-6 binds to IL-6R, and the IL-6/IL-6R complex associates with gp130 which dimerizes and initiates intracellular signaling. Cells that only express gp130 but no IL-6R cannot be stimulated by IL-6 unless a soluble form of the IL-6R is present. This type of signaling has been shown for hematopoietic progenitor cells, endothelial cells, and smooth muscle cells. In this paper we show that purified recombinant vIL-6 binds to gp130 and stimulates primary human smooth muscle cells. IL-6R fails to bind vIL-6 and is not involved in its signaling. A Fc fusion protein of gp130 turned out to be a potent inhibitor of vIL-6. Our data demonstrate that vIL-6 is the first cytokine which directly binds and activates gp130. This property points to a possible role of this viral cytokine in the pathophysiology of human herpes virus 8.

Kaposi's sarcoma-associated herpesvirus-encoded interleukin-6

Since the discovery of the virus in 1994, the rapid pace with which Karposi's sarcoma-associated herpesvirus (KSHV) research has progressed has quickly led to a broad understanding of the structure of the virus and its biology and pathology in humans. Molecular piracy of potentially useful cellular genes has emerged as a characteristic feature of this virus. The viral homolog of human IL-6, vIL-6 is an example in kind. Studies in vitro and in vivo have shown that vIL-6 can stimulate the growth of KSHV-infected primary infusion lymphoma (PEL) cells, can promote hematopoiesis, and act as an angiogenic factor through the induction of vascular endothelial growth factor (VEGF). It is not difficult to envision how vIL-6, through these properties and perhaps others yet to be identified, can contribute to KSHV survival and spread in the human population.

Serologic prevalence of antibody to human herpesvirus type 8 in patients with various monoclonal gammopathies

Both viral and serologic studies have consistently shown an association of human herpesvirus type 8 (HHV-8) with Kaposi's sarcoma, primary effusion lymphoma, and Castleman's disease. The presence of HHV-8 DNA in patients with myeloma has been reported by some investigators but not substantiated by others. In addition, variable results have been obtained with serologic studies for HHV-8 in patients with myeloma and certain other monoclonal gammopathies (MG). We tested 238 coded serum or plasma samples from 96 patients with various MG for antibodies to lytic and latent HHV-8 antigens by indirect immunofluorescence. Thirty-four of 96 (35%) patients were positive for the lytic antibody, but none were positive for the latent antibody. Patients with kappa or lambda light chain myeloma were often positive for the lytic antibody when compared to patients with IgG or IgA myeloma (8 of 11 [73%] vs. 12 of 38 [32%], P = 0.033). The patients with light chain myeloma also were more likely to be positive when compared to patients with Waldenström's macroglobulinemia (WM) (4 of 15 [27%], P = 0.045) or AL amyloidosis (4 of 13 [31%], P = 0.047). Four of 9 (44%) patients with monoclonal gammopathy of undetermined significance (MGUS) were positive. However, 4 other patients who progressed from MGUS to myeloma were negative. Subgroup analysis of MG may help clarify the role of HHV-8 in these disorders.

Occurrence of primary cancers in association with multiple myeloma and Kaposi's sarcoma in the United States, 1973-1995

The causes of multiple myeloma (MM) are obscure, but a laboratory association was recently reported between MM and human herpesvirus 8 (HHV-8), the probable etiologic agent of Kaposi's sarcoma (KS). Although there has been some additional laboratory corroboration, most laboratory studies have found no association between MM and HHV-8. We looked for indirect evidence of an HHV-8/MM association by evaluating whether MM is associated with KS in the United States. Cancer incidence and survival data were obtained from the Surveillance, Epidemiology, and End Results (SEER) program for the years 1973-1995. Strength of association was assessed for a number of cancer pairs using standardized incidence ratios (SIRs) (observed/expected double cancers). KS was strongly associated (SIR > 15) with non-Hodgkin's lymphoma and anal cancer, was modestly associated (2.5 < SIR < 5.5) with MM, Hodgkin's disease, and testicular cancer and was not significantly associated with 6 other cancers. Besides being associated with KS, MM was weakly associated (1.7 < SIR < 2.3) with Hodgkin's disease and testicular cancer. The SIRs for 7 other cancers paired with MM were all less than 1.6. Factors that might be responsible for the KS/MM association include MM-related immune dysfunction, HIV and HHV-8, but the role of these factors cannot be directly assessed through the SEER database. Although we cannot rule out the possibility that HHV-8 is linked to a small proportion of MM cases, the modest KS/MM association is evidence that the vast majority of MM cases are not likely to be associated with HHV-8.