Francesca Giannelli

Prevalence of bcl-2 Rearrangement in Patients with Hepatitis C Virus–Related Mixed Cryoglobulinemia with or without B-Cell Lymphomas

Context Rearrangement of bcl-2 has an antiapoptotic effect and has been implicated as a potential cause of benign lymphoproliferation (causing mixed cryoglobulinemia) and B-cell lymphoma. Mixed cryoglobulinemia is strongly associated with hepatitis C virus (HCV) infection. Contribution In patients with HCV-associated chronic liver disease, bcl-2 rearrangement occurred significantly more often in patients with chronic HCV infection and mixed cryoglobulinemia than in HCV-infected patients without mixed cryoglobulinemia; it also occurred in three of four patients with B-cell lymphoma. Transient suppression of HCV in two patients was associated with remission of clinical manifestations of mixed cryoglobulinemia. Implications Viral induction of gene sequence translocations may help explain some benign and malignant lymphoproliferative disorders. The Editors Mixed cryoglobulinemia is a distinct syndrome clinically characterized by purpura; weakness; arthralgia; and such conditions as membranoproliferative glomerulonephritis, peripheral neuropathy, skin ulcers, and diffuse vasculitis (1, 2). Cryoprecipitable immune complexes, specifically mixed (IgG-IgM) cryoglobulins, are the serologic hallmark of the disease. Immunoglobulin Gs are the autoantigens, and IgMs with rheumatoid factor activity are the autoantibodies. Mixed cryoglobulinemia is classified as type II or type III according to the presence of polyclonal or monoclonal IgMs (3, 4). Because expansion of rheumatoid factorproducing B cells is the underlying disorder of mixed cryoglobulinemia, this condition is considered a benign B-cell lymphoproliferative disease. Type II and III mixed cryoglobulinemia are similar in terms of organ involvement and clinical course, except that type II disease may evolve into cancer. Type II mixed cryoglobulinemia is often observed in conjunction with bone marrow findings consistent with indolent B-cell lymphoma (5-9) and evolves to frank B-cell malignancy in about 10% of cases (10). A strong association between mixed cryoglobulinemia and infection with hepatitis C virus (HCV), a hepatotropic and lymphotropic virus (10, 11), has been shown. A pathogenetic role of chronic infection with HCV in mixed cryoglobulinemia has been suggested. The mechanisms involved in benign lymphoproliferation of mixed cryoglobulinemia and its evolution to lymphoma remain unknown. However, rearrangement of the antiapoptotic B-cell lymphoma/leukemia 2 (bcl-2) genethe t(14;18) translocationis suggested to play a role in the pathogenesis of HCV-associated mixed cryoglobulinemia (12, 13). The t(14;18) translocation, the most frequent genetic aberration in human lymphoma (14, 15), may be favored by sustained, strong antigenic stimulation (16-18). As a result of bcl-2 rearrangement, the bcl-2 gene on chromosome 18q21 is coupled with the immunoglobulin heavy chain gene (IgH) on chromosome 14q32 by a process frequently involving IgH joining segments (JH) (Figure 1, top). At the junction of the two genes, insertions of variable lengths (N segments) due to random addition of nongermline nucleotides result in a DNA pattern that is clone specific (19, 20). As a consequence of this rearrangement, bcl-2 is activated and B cells bearing the t(14;18) translocation express inappropriately elevated levels of the Bcl-2 protein. Figure 1. Schematic representation of the t(14; 18) translocation and its effects on B cells. Top. bcl-2 Bottom. Bcl-2 is a member of a larger family. Family members can interact with each other in a complex manner; some act to promote and others to inhibit apoptosis (14). The Bcl-2 protein protects cells from apoptosis, whereas its homologue, Bax, kills cells (21). Thus, the ratio of Bcl-2 to Bax is a determinant of susceptibility to apoptosis (14) (Figure 1, bottom). Strong expression of Bcl-2 protein has been observed in lymphoid infiltrates in liver and bone marrow specimens of patients with mixed cryoglobulinemia (22). In a previous study, the prevalence of bcl-2 rearrangement in peripheral blood mononuclear cells was significantly higher in patients with chronic HCV infection than in healthy persons or those without HCV infection but with chronic liver diseases or systemic autoimmune disorders (13). Of note, the prevalence of bcl-2 rearrangement was particularly high in patients with HCV-associated type II mixed cryoglobulinemia. We sought to evaluate the prevalence of bcl-2 rearrangement in peripheral blood cells of patients with mixed cryoglobulinemia, to confirm that results are patient specific by sequencing studies, to analyze Bcl-2 expression and the ratio of Bcl-2 to Bax in these patients, and to observe the effect of antiviral therapy. Methods Patients We enrolled 37 patients (12 men and 25 women; mean age SD, 64 9 years) with HCV infection and mixed cryoglobulinemia who were consecutively referred to the outpatient clinic of the Department of Internal Medicine, University of Florence School of Medicine, a tertiary hepatology center, and the rheumatologic section of the Department of Internal Medicine, University of Pisa School of Medicine, from January 1999 to May 2000. These patients were compared with 101 consecutively recruited patients (62 men and 39 women; mean age, 51 11 years) who had HCV-related chronic liver diseases but not mixed cryoglobulinemia or another lymphoproliferative disease. Hepatitis C virus infection was established by detection of circulating anti-HCV antibodies (EIA-2 and RIBA-2, Ortho Diagnostic Systems, Raritan, New Jersey) and HCV RNA (nested polymerase chain reaction [PCR] for HCV) (10, 13, 23). Essential mixed cryoglobulinemia was diagnosed according to published criteria (10, 13). Serum cryoglobulins, complement fraction levels, rheumatoid factor, and autoantibodies were routinely measured and characterized in all patients as described elsewhere (10, 13, 23). Diagnosis of liver disease was based on results of liver biopsy. Lymphomas were diagnosed by an independent pathologist and classified according to the revised European-American classification of lymphoid neoplasms (24). No patient tested positive for hepatitis B surface antigen, IgM anti-HBc, hepatitis B virus DNA, IgM anti-delta, antiEpsteinBarr virus, anti-cytomegalovirus, antiherpes simplex virus, or anti-HIV. No patient had a history of alcohol abuse or previous antiviral or immunosuppressive treatment. All patients gave informed consent to participate in the study, which was performed in accordance with the principles of the Declaration of Helsinki, and the study was approved by the local ethics committee. Detection of the t(14; 18) Translocation The t(14; 18) translocation in peripheral blood mononuclear cells was detected on total DNA by using nested PCR (major breakpoint region), as described elsewhere (13). Nested PCR is a variant of PCR; after an initial series of amplification cycles, templates are again amplified by using a second set of primers internal to the first ones. The resulting reaction is very specific and sensitive owing to specific binding to the target sequences of four instead of two specific primers. The limit of sensitivity was one rearranged cell in 105 to 106 normal cells. Amplification products were analyzed by both ethidium bromide staining and hybridization with a specific digoxigenin-labeled probe (Southern blot analysis). Each sample was analyzed at least twice, and all samples that tested negative on PCR were analyzed at least four times. Different cell samples that were obtained at the same time (synchronous) or at different times (metachronous) were also analyzed when possible. Approximately 2.5 105 mononuclear cells were tested in each reaction, corresponding to about 1 g of DNA. Positive and negative control samples were included in each experiment (13). To avoid false-positive results caused by carryover of PCR product, precautions were taken, as described elsewhere (10, 13). To ensure DNA amplificability, PCR was also performed by using primers for the human HLA gene (exon 2 of HLA-DRB gene), as previously reported (13). Finally, bcl-2/JH junction sequence was determined in part by cycle sequencing and solid-phase sequencing techniques (13, 25) and in part by automated sequencing (Abi Prism, Perkin Elmer, Norwalk, Connecticut). Measurement of Bcl-2 and Bax Proteins Bcl-2 and Bax proteins were measured as described elsewhere (13) on freshly isolated peripheral blood mononuclear cells and, when possible (9 patients), in separated cell subgroups (T cells, B cells, and monocytes and macrophages). Bcl-2 was detected by using monoclonal mouse anti-human Bcl-2 (Santa Cruz Biotechnology, Inc., Santa Cruz, California), and Bax was detected by using polyclonal rabbit anti-human Bax (Upstate Biotechnology, Inc., Lake Placid, New York). The CD2+ T cells, CD19+ B cells, and CD14+monocytes and macrophages from peripheral blood were separated by immunomagnetic isolation using Dynabeads M450 Pan-T, M-450 Pan-B, and M-450 CD14+, respectively (Dynal A.S., Oslo, Norway), according to the manufacturers instructions. Statistical Analysis Data are expressed as the mean SD. Data were analyzed by performing the Fisher exact test, using True Epistat 4.0 statistical software (Epistat Service, Richardson, Texas). A P value less than 0.05 was considered significant. Role of the Funding Sources The funding sources had no role in the analysis, reporting, or interpretation of the data or in the decision to submit the report for publication. Results The Table shows the clinical, epidemiologic, and pathologic characteristics of patients with HCV-related mixed cryoglobulinemia. The mean duration of mixed cryoglobulinemia syndrome was 9.2 5.2 years. Most of these patients (91%) had chronic liver diseases. Liver biopsy showed chronic hepatitis in 27 patients (72.9%) and cirrhosis in 7 patients (18.9%); of the latter patients, 1 also had superimposed hepatocellular carcinoma. Liver biopsy was not performed in the remaining 3 patients becaus

Relevance of inapparent coinfection by hepatitis B virus in alpha interferon-treated patients with hepatitis C virus chronic hepatitis.

The aim of the study was to investigate whether an “inapparent” coinfection by hepatitis B virus (HBV) in anti‐HCV‐positive chronic liver disease patients may influence interferon (IFN) response. Fourteen anti‐HCV‐positive, hepatitis B surface antigen (HBsAg)‐negative but serum HBV‐DNA‐positive patients and 111 anti‐HCV‐positive, HBsAg‐negative, and HBV‐DNA‐negative patients with chronic hepatitis were treated with 3 MU of recombinant α‐2a IFN 3/week for 1.2 months. Serum HBV‐DNA and HCV‐RNA were determined before treatment, after 6–12 months, and at the time of alanine aminotransferase (ALT) flare‐up by HBV polymerase chain reaction (PCR) and HCV PCR, respectively. IgM anti‐HBc were tested using the IMx Core‐M assay (Abbott Laboratories, North Chigago, IL). By the end of treatment, ALT values had become normal in 4/14 HBV‐DNA‐positive patients (28%), but all “responders” (4/4) relapsed. IgM anti‐HBc was detected both before treatment and during ALT elevation in three patients and only during ALT relapse in another three. In the remaining 111 patients, a biochemical response to IFN treatment was observed in 54% and relapse of ALT values in 47%. “Inapparent” HBV/HCV coinfection may be implicated in cases of resistance to IFN. HBV replication and HBV‐related liver damage may persist in patients in whom HCV replication was inhibited by current doses of IFN, as suggested also by the presence of IgM anti‐HBc in some cases. Further studies will show the effect of different treatment schedules. HBV‐DNA and/or IgM anti‐HBc detection with very sensitive methods may be important both as a prognostic factor and as a tool for better understanding of intervirus relationships and mechanisms involved in multiple hepatitis virus infections. J. Med. Virol. 51:313–318, 1997.

Prevalence of mixed infection by different hepatitis C virus genotypes in patients with hepatitis C virus–related chronic liver disease☆☆☆★

Multiple infection by different hepatitis C virus (HCV) genotypes may be of great clinico-pathologic interest. In this study we determined the effective prevalence of coinfections by two or more HCV genotypes in 213 subjects with HCV-positive chronic hepatitis by using genotype-specific polymerase chain reaction (PCR), genotype-specific probe hybridization, and direct sequencing. The most prevalent genotype was HCV-1b (54%). HCV-2 (a/c) was also prevalent (27%), and types 1a and 3a were found in 5% and 3% of patients, respectively. A mixed infection was detected in 23 patients (10.8%): 4 out of 23 were coinfected by types 1a + 1b, while the remaining 19 patients had a b + 2 (a/c) mixed infection. Further analysis based on restriction fragment length polymorphism (RFLP) on type-specific PCR products was used to verify genotyping results. Only four coinfections (1a + 1b in 2 patients and 1b + 2 (a/c) in the remaining 2 patients, respectively) were confirmed by enzyme cleavage. All patients with true coinfection had long-lasting infection and liver cirrhosis. Both true and false mixed infections resulting from RFLP analysis were confirmed by direct sequencing of type-specific amplification products. We also determined a recurrent C/T transversion at position 618 in all sequenced samples. In 4 cases another point mutation (G/A at position 626) was found, reducing the number of mismatches between HCV-2 and HCV-1b from 4 to 3 (or 2). Interestingly, all HCV-2 isolates sequenced showed the highest degree of nucleotide homology with HCV-2 subtype c, confirming the relatively high prevalence of this subtype in Italy. In conclusion, we showed the possibility of multiple infection by different HCV types in the general population of chronically infected patients without particular risk factors, even if in a low percentage of cases. Further studies are needed to assess the clinical relevance of chronic HCV infection with multiple genotypes.

Impaired response to alpha interferon in patients with an inapparent hepatitis B and hepatitis C virus coinfection

SummaryThe possibility of hepatitis B virus (HBV) infection in HBsAg-negative patients has been shown. However, an “inapparent” coinfection by HBV in hepatitis C virus (HCV)-positive patients generally is not taken into account in clinical practice. Mechanisms responsible for resistance to interferon (IFN) have not been completely clarified. The aim of this study was to investigate whether an “inapparent” coinfection by HBV in anti-HCV-positive chronic liver disease patients may influence IFN response. Fourteen anti-HCV positive, HBsAg-negative but serum HBV DNA-positive patients by PCR and 111 anti-HCV-positive, HBsAg-negative and HBV DNA (PCR)-negative patients with chronic hepatitis were treated with 3 MU of recombinant α-2a IFN 3 times weekly for 12 months. Serum HBV DNA and HCV RNA were determined before treatment, after 6–12 months and in coincidence with ALT flare-up by PCR. HBV PCR was performed using primers specific for the S region of the HBV genome and HCV PCR with primers localised in the 5′NC region of HCV genome. IgM anti-HBc was tested using IMx Core-M Abbott assay. By the end of treatment, ALT values had become normal in 4/14 HBV DNA-positive patients (28%), but all “responders” (4/4) relapsed between 2 and 5 months after therapy. All but one patient were HCV RNA-positive before treatment, 6 were also both HBV DNA and HCV RNA-positive during ALT flare-ups. In 5 patients, only HBV DNA and in 3 patients, only HCV RNA was detected when transaminase values increased. All patients remained HBsAg-negative and anti-HCV-positive. IgM anti-HBc was detected both before treatment and during ALT elevation in 3 patients and only during ALT relapse in 3 others. Of the 111 anti-HCV positive, HBsAg-negative and HBV DNA (PCR)-negative patients with chronic hepatitis, a biochemical response to IFN treatment was observed in 54% of the cases. Relapse of ALT values was observed in 47% of the cases during a follow-up of 1 year after treatment. “Inapparent” HBV/HCV coinfection may be implicated in cases of resistance to IFN treatment. In addition, HBV replication may persist in patients in whom HCV replication was inhibited by IFN treatment. The pathogenic role of HBV in liver disease was confirmed by detection of IgM anti-HBc in some cases; the appearance of these antibodies only after IFN treatment suggests that IFN may exert a selective role in favour of HBV. Further studies will show the effect of different treatment schedules. HBV DNA and/or IgM anti-HBc detection with very sensitive methods may be important both as a prognostic factor and as a tool for better understanding interviral relationships and mechanisms involved in multiple hepatitis virus infections.

Association between mixed cryoglobulinemia, translocation (14;18), and persistence of occult HCV lymphoid infection after treatment

We read with interest the article by Sansonno et al.,1 who investigated 16 consecutive patients with hepatitis C virus (HCV)-positive chronic liver disease, including 8 with lymphoproliferative disorders (LPDs): 5 with mixed cryoglobulinemia (MC) (3 with type II), and 3 with monoclonal gammopathy of undetermined significance (MGUS). Translocation (14;18) was not detected in peripheral blood mononuclear cells (PBMCs), single portal tract inflammatory infiltrates, or liver biopsy sections. In spite of the small number of patients tested, this study offers interesting data with regard to the accurate analysis of t(14;18)-negative MC patients. In fact, t(14;18) was previously shown to be significantly associated with MC—especially type II—in several reports over the last 9 years using polymerase chain reaction–based methods and fluorescence in situ hybridization.2–9 Translocation (14;18) was detected in the PBMCs of HCV-positive patients in 99 of 364 (27.2%) without LPDs and in 85 of 151 (56.3%) with LPDs, including 78 of 128 (60.9%) with MC and 7 of 23 (30.4%) with B cell non-Hodgkin’s lymphoma (NHL). No association was reported between t(14;18) and MGUS. In type II MC (the form possibly evolving in NHL), t(14;18)-positive B cells were also shown to be clonally expanded and characterized by altered Bcl-2/Bax ratio, indicating their expanded life.6 Furthermore, these clones may regress following antiviral treatment and expand again after viral relapse.6,7 Bcl-2 overexpression was also shown in the bone marrow and liver infiltrates of MC patients, as well as in 1 case of HCV-positive, t(14;18)-negative MC.10 Overall, the available data strongly suggest that Bcl-2–related expanded B cell life is important in the pathogenesis of MC and possibly other HCV-related LPDs, and that t(14;18) may represent, in most cases, a key factor. In the study by Sansonno et al.,1 neither t(14;18) nor Bcl-2 overexpression were detected, and the hypothesis that the challenge of liver lymphoid infiltrates with viral epitopes represents the key factor in MC pathogenesis was suggested. In this respect, data we recently obtained may be of interest. We analyzed 9 consecutive HCV-positive patients with MC who showed sustained virological response after treatment. An extensive follow-up showed persistent HCV RNA negativity both in serum and liver samples via very sensitive detection methods (Table 1). In contrast, mitogen-stimulated11 and uncultured PBMCs were HCV RNA–positive in 5 cases (Table 1). Detection of negative-strand HCV RNA via Tthbased reverse-transcriptase polymerase chain reaction confirmed active cell infection in most cases. Interestingly, isolated lymphatic infection was strictly associated with the persistence of both MC-syndrome and t(14;18)-bearing B cell clones (Table 1). On one hand, these data confirm the frequent association between t(14;18) and MC in our geographic area. On the other hand, they strongly suggest that the pathogenesis of MC is not necessarily related to the intrahepatic challenge between HCV epitopes and lymphoid infiltrates. Further studies investigating the possible role played by lymphatic infection in HCV is important. In conclusion, available data suggest that MC and other HCVrelated LPDs recognize different pathogenetic pathways leading to a similar clinical picture. An accurate understanding of these different pathways, as well as the frequency of their involvement in the pathogenetic mechanisms, is essential for the correct appraisal of both therapeutic and preventive measures.

Serum HCV-RNA and Liver Histologic Findings in Patients with Long-Term Normal Transaminases

In this study we aimed to correlate liverhistology and the presence of hepatitis C virus (HCV)viremia, genotype, and quantity of HCV genome in 19positive and 11 RIBA II indeterminate patientspresenting persistently normal ALT values over 24 monthsbefore biopsy. In addition, after biopsy serum ALTvalues were monitored monthly for a mean follow-upperiod of 24.8 months, after which patients werereevaluated for RIBA II and the presence of viremia.Sixteen patients (53%) were serum HCV-RNA-positive; 13of them (68%) were confirmed positive and 3 (27%)indeterminate on RIBA II. Histology of the HCV-RNA-positive patients showed eight cases of CPH (one case ofgenotype 1a; four cases type 1b; three cases type 2),six cases of CAH (three cases type 1b, three cases type2), one case of CLH (type not determined), and one case of normal liver (NL) (type 1b).Histology of the HCV-RNA-negative patients showed fourcases of CPH, one case of CAH, two cases of CLH, andseven cases of NL. During the follow-up period ninepatients (30%) presented slight increases in ALT values(<2 × N), and in particular, flares of ALT wereobserved four times in the CAH and five times in the CPHpatients, who were all viremic, but never in the NL subjects. These results indicate that subjectspositive on RIBA II, but with persistently normal ALTvalues, had a high probability of being serumHCV-RNA-positive and that almost all these viremicsubjects presented histologic signs of liver disease. Incontrast, RIBA II indeterminate subjects had a moderateprobability of being HCV-RNA-positive, but a number ofthese may present signs of liver disease. In both cases there was no association withgenotype or HCV-RNA serum levels. The other nonviremiccases included subjects with hepatic changes goingtoward resolution or with normal liver in whom hepatic biopsy can be avoided. Only one case was a truecarrier since he was viremic with normal liver andpersistently normal ALT values.

Hepatitis C virus core protein expression in human B-cell lines does not significantly modify main proliferative and apoptosis pathways.

Hepatitis C virus (HCV) chronic infection has been associated with many lymphoproliferative disorders. Several studies performed on hepatoma and fibroblast cell lines suggest a role of the HCV core protein in activation of cellular transduction pathways that lead to cell proliferation and inhibition of apoptosis. However, no data are available concerning the effects of HCV core expression on B-lymphocyte proliferation and apoptosis. B-lymphocyte cell lines permanently expressing full-length HCV 1b core sequences isolated from chronically infected patients were established using B-cell lines at different degrees of differentiation. Clones and pools of clones permanently expressing the HCV core were selected and characterized for protein expression by Western blot and FACS. Expression of HCV core proteins did not significantly enhance cell proliferation rates under normal culture conditions or under mitogenic stimulation. Analysis of NF-kappa B, CRE, TRE and SRE pathways by luciferase reporter genes did not show a significant influence of HCV core expression on these signal transduction cascades in B-lymphocytes. The effects of HCV core on anti-IgM and anti-FAS-induced apoptosis in B-cell lines was also analysed. In this experimental model, HCV core expression did not significantly modify the apoptotic profile of the B-lymphocyte cell lines tested. These data underline a cell type-specific effect of HCV core expression. In fact, it was not possible to show a significant contribution of the HCV core protein in activation of the major B-cell signal transduction pathways involved in the regulation of proliferation and programmed cell death, which is in contrast with the results reported in hepatoma cell lines.

Modifications of plasma platelet-activating factor (PAF)-acetylhydrolase/PAF system activity in patients with chronic hepatitis C virus infection

Summary.  Hepatitis C virus (HCV) chronically infects about 200 million individuals worldwide and leads to severe liver and lymphatic diseases. HCV circulates in the serum, associated with apoB‐containing lipoproteins. Platelet‐activating factor (PAF), a pro‐inflammatory mediator, is mainly modulated by plasma PAF‐acetylhydrolase (pPAF‐AH), associated with ApoB100‐containing low‐density lipoproteins (LDL). The aim of the study was to evaluate the potential effects of chronic HCV infection on the PAF/pPAF‐AH system. HCV‐RNA was detected in plasma, peripheral blood mononuclear cells (PBMC) and liver samples. Plasma PAF levels, pPAF‐AH activity, ApoB100 serum titres and pPAF‐AH mRNA levels in cultured macrophages were determined. Plasma PAF levels were significantly higher and pPAF‐AH activity was significantly lower in HCV patients than in controls. No significant modifications of pPAF‐AH mRNA in macrophages or in ApoB100 values were observed in HCV patients compared with controls. Patients who cleared HCV after antiviral treatment showed a complete restoration of pPAF‐AH activity and significant decrease of PAF levels during the follow‐up. No data exist about the PAF/pPAF‐AH system behaviour during HCV infection. This study shows that in HCV patients modifications of pPAF‐AH activity/PAF levels take place and that HCV clearance restored pPAF‐AH activity. This suggests that circulating viral particles play a role in PAF/pPAF‐AH system modifications and such an alteration could be involved in HCV‐related damage.

Effect of chronic hepatitis C virus infection on inflammatory lipid mediators

BACKGROUND Platelet-activating factor (PAF), a powerful phospholipid mediator of inflammation, is degraded by plasma PAF-acetyl-hydxolase (pPAF-AH), an enzyme which circulates in serum mainly in a complex with lipoproteins that confer its biological activity. Hepatitis C virus (HCV) is linked to lipoproteins in serum too. Reduced pPAF-AH activity was observed in several diseases, including systemic vasculitis. AIM To evaluate if chronic HCV infection could alter pPAF-AH physiological functions. SUBJECTS 145 subjects were studied: 56 HCV- and 52 HBV-infected patients (pathologic controls); 37 healthy subjects (healthy controls). METHODS pPAF-AH activity, PAF and Apo B100 titers were determined in plasma; enzyme expression levels were evaluated in monocyte-derived macrophages. HCV-RNA was detected in plasma, peripheral blood mononuclear cells and liver samples. RESULTS HCV-infected patients showed an increase of PAF levels following a significant decrease of pPAF-AH activity. A recovery of pPAF-AH activity occurs only in patients who clear HCV after the antiviral treatment. Expression levels of pPAF-AH mRNA and Apo B100 titers were not modified in HCV patients in comparison to controls. CONCLUSION In light of these results, it is tempting to hypothesize that during chronic HCV infection, the PAF/pPAF-AH system may be altered and this condition may contribute to HCV-related vascular damage.

Hepatitis C Virus Lymphotropism and Possible Pathogenetic Implications.

Hepatitis C virus (HCV) is a virus that contains a single-stranded positive-sense RNA genome and is distantly related to the flaviviruses and pestiviruses. Following its discovery, the identification at a structural level of existing analogies between HCV and Pesti- and Flavivirus, has become a basis for research in evaluating whether common aspects in the natural history of such infections exist. One of these analogies is the possibility to infect elements of the lymphatic system (lymphotropism). This viral characteristic is of interest in regards to possible clinical and pathological consequences. In particular, one of the most intringuing hypotheses concerns the possibility that HCV lymphotropism may represent at least one of the “missing links” between HCV infection and some lymphoproliferative disorders frequently observed in association with this infection. Studies performed in this field are in agreement with this hypothesis. However the direct demonstration is still lacking and clarification of the mechanisms eventually in play deserves further study.