Risk of non-Hodgkin lymphoma and lymphoproliferative precursor diseases in US veterans with hepatitis C virus

Prevalence of hepatitis C serum antibody in autoimmune diseases

OBJECTIVE

To evaluate the prevalence of serum antibodies against hepatitis C virus and other infectious agents in a large cohort of well-characterized patients with autoimmune diseases (AID).

METHODS

We utilized 1322 sera from patients with 18 different AID and 236 sera from healthy controls from the same countries and with similar age and sex distribution. All sera were tested for the presence of serum anti-hepatitis C virus (HCV) antibodies as well as antibodies directed at other infectious agents and autoantibodies.

RESULTS

Anti-HCV antibody was detected in 115/1322 (8.7%) of patients with AID and 0.4% of matched healthy controls (P < 0.0001). The prevalence of anti-HCV antibody was significantly higher in 7/18 different AID (i.e. cryoglobulinemia, mixed cryoglobulinemia pemphigus vulgaris, vasculitis, secondary anti-phospholipid syndrome, Hashimoto's thyroiditis, and inflammatory bowel disease) compared to controls. Patients with AID and serum anti-HCV positivity had an increased prevalence of antibodies against hepatitis B virus, Toxoplasma gondii and Cytomegalovirus as opposed to a lower frequency of serum autoantibodies.

CONCLUSIONS

The enhanced prevalence of anti-HCV serum antibodies in AID may suggest a role for HCV in tolerance to breakdown, similarly to its established role in mixed cryoglobulinemia. This immune mediated effect does not rule out the role of other infectious agents.

Characterization of the light chain-restricted clonal B cells in peripheral blood of HCV-positive patients

To investigate the association between hepatitis C virus (HCV) and B cell proliferation, we searched for the clonal B cells by flow cytometric analysis of the surface immunoglobulin kappa (kappa):lambda (lambda) light chain ratios of the circulating B (CD19+) cells in 240 HCV-positive patients and 150 negative controls with liver diseases. Clonal B cells with light chain restriction (kappa:lambda ratio >3:1 or <1:2) were analyzed for CD5 expression and the presence of monoclonal immunoglobulin heavy-chain (IGH) gene rearrangements and the t(14;18) chromosomal translocation. Clonal B cells were detected in 7 cases with HCV (2.9%), but was never detected in the controls (p < 0.05). Of the 7 cases, all had monoclonal IGH gene rearrangements and one had the t(14;18) chromosomal translocation. These HCV-related clonal B cells are not uniform in the intensity of CD5 expression and showed no increase in the frequencies of CD5+ population compared with non-clonal B cells. No "chronic lymphocytic leukemia-phenotype" cells were found. The loss of clonality was observed in 2 cases treated with interferon and in one case treated with splenectomy. The longitudinal study is required to determine whether these circulating clonal B cells progress to lymphoproliferative disorders in future or not.

Risk of immune thrombocytopenic purpura and autoimmune hemolytic anemia among 120 908 US veterans with hepatitis C virus infection

BACKGROUND

There is emerging evidence that hepatitis C virus (HCV) infection play a role in the etiology of immune thrombocytopenia purpura (ITP) and autoimmune hemolytic anemia (AIHA), both of which are severe autoimmune cytopenias.

METHODS

To determine if HCV infection increases the risk for ITP and AIHA, we calculated the incidence rates of ITP and AIHA among 120 691 HCV-infected and 454 905 matched HCV-uninfected US veterans who received diagnoses during the period 1997 to 2004. After excluding individuals with a prior diagnosis of a lymphoproliferative disease, human immunodeficiency virus, or cirrhosis, we fitted Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) as measures of risks.

RESULTS

We found 296 ITP and 90 AIHA cases. Among HCV-infected vs HCV-uninfected persons, the overall incidence rates of ITP were 30.2 and 18.5 per 100 000 person-years, and for AIHA they were 11.4 and 5.0 per 100 000 person-years, respectively. Hepatitis C virus was associated with elevated risks for ITP (HR, 1.8; 95% CI, 1.4-2.3) and AIHA (HR, 2.8; 95% CI, 1.8-4.2). The ITP incidence was increased among both untreated and treated HCV-infected persons (HR, 1.7; 95%, CI, 1.3-2.2 and HR, 2.4; 95% CI, 1.5-3.7, respectively), whereas AIHA incidence was elevated only among treated HCV-infected persons (HR, 11.6; 95% CI, 7.0-19.3).

CONCLUSIONS

Individuals infected with HCV are at an increased risk for ITP, whereas the development of AIHA seems to be associated with HCV treatment. It may be beneficial to test individuals newly diagnosed as having ITP for HCV infection.

Autoimmunity and lymphomagenesis

For more than 50 years, links between autoimmunity and lymphomas have been described based on human and animal studies. Over the last 3 decades, many studies have addressed specific hypotheses about these associations using population level data. This has been accomplished by assessing previous autoimmune history in case-control studies of patients with lymphoma (mainly non-Hodgkin lymphoma) and myeloma, and by following cohorts of patients with various autoimmune diseases for subsequent development of lymphoma and multiple myeloma. In this article, we review our recently published series of association studies based on data from Scandinavia and from US Veterans and other relevant findings. We also discuss what these associations have revealed about the mechanisms and pathways underlying both autoimmunity and lymphoma. Finally, we discuss the future directions involving a combination of population and molecular studies that are needed to better define underlying biological mechanisms.

Genetics- and immune-related factors in the pathogenesis of lymphoplasmacytic lymphoma/ Waldenström's macroglobulinemia

There are emerging data to support a role for genetic and immune-related factors in the pathogenesis of lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia. In this article, we review our recently published, large, population-based studies using data from Sweden and from United States veterans and propose mechanisms and pathways underlying our observations. We also discuss future directions for new studies designed to increase our current knowledge and to define underlying biologic mechanisms of our findings. Finally, based on novel insights on this topic, we discuss clinical implications and provide perspective on the relevance of these data for patient counseling and clinical follow-up.

Impact of hepatitis C virus seropositivity on survival after allogeneic hematopoietic stem cell transplantation for hematologic malignancies

BACKGROUND

Because hepatitis C virus infection causes hepatic and immunological dysfunction, we hypothesized that seropositivity for this virus could be associated with increased non-relapse mortality after allogeneic hematopoietic stem cell transplantation.

DESIGN AND METHODS

We performed a case-control study of the outcomes of patients who were hepatitis C virus seropositive at the time of allogeneic hematopoietic stem cell transplantation (N=31). Patients positive for hepatitis C virus were considered candidates for stem cell transplantation only if they had no significant evidence of hepatic dysfunction. Matched controls (N=31) were seronegative for viral hepatitides and were paired according to age, diagnosis, disease stage, conditioning regimen and donor type. We also compared the hepatitis C virus seropositive patients to all seronegative patients (all controls, N=1800) transplanted during the same period, to adjust for other confounding effects.

RESULTS

The median age of the seropositive patients was 49 (range 26-72); 15 had acute myeloid leukemia/myelodysplastic syndrome, 6 had chronic myeloid leukemia/myeloproliferative disease, 6 non-Hodgkin's lymphoma, 2 myeloma, 1 acute lymphocytic leukemia and 1 Hodgkin's lymphoma; 61% had poor risk disease; 68% had related donors; 68% received reduced intensity conditioning; 7 patients had mildly abnormal alanine transaminase levels (all less than three times the upper limit of normal) and 1 patient had minimally elevated bilirubin. These characteristics were similar to those of the matched control group. Median overall survival was 3, 18 and 20 months, and 1-year survival was 29%, 56% and 56%, in the hepatitis C virus, matched and all controls groups, respectively (hazard ratio for death 3.1, 95% confidence interval 1.9-5.6, p<0.001 in multivariate analysis). Non-relapse mortality at 1 year was 43%, 24% and 23%, respectively (hazard ratio 3.3, 95% confidence interval 1.8-7.1, p<0.01). Disease progression and graft-versus-host disease rates were comparable.

CONCLUSIONS

Hepatitis C virus seropositivity is a significant risk factor for non-relapse mortality after allogeneic hematopoietic stem cell transplantation even in patients with normal or minimally abnormal liver function tests.

Risk of plasma cell and lymphoproliferative disorders among 14621 first-degree relatives of 4458 patients with monoclonal gammopathy of undetermined significance in Sweden

Familial clustering of the precursor condition, monoclonal gammopathy of undetermined significance (MGUS) has been observed in case reports and in smaller studies. Using population-based data from Sweden, we identified 4458 MGUS patients, 17505 population-based controls, and first-degree relatives of patients (n = 14621) and controls (n = 58387) with the aim to assess risk of MGUS and lymphoproliferative malignancies among first-degree relatives of MGUS patients. Compared with relatives of controls, relatives of MGUS patients had increased risk of MGUS (relative risk [RR] = 2.8; 1.4-5.6), multiple myeloma (MM; RR = 2.9; 1.9-4.3), lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM; RR = 4.0; 1.5-11), and chronic lymphocytic leukemia (CLL; RR = 2.0; 1.2-2.3). Relatives of patients with IgG/IgA MGUS had a 4.0-fold (1.7-9.2), 2.9-fold (1.7-4.9), and 20-fold (2.3-170) elevated risk of developing MGUS, MM, and LPL/WM, respectively. Relatives of IgM MGUS patients had 5.0-fold (1.1-23) increased CLL risk and nonsignificant excess MM and LPL/WM risks. The results were very similar when we assessed risk by type of first-degree relative, age at MGUS (above/below 65 years), or sex. Risk of non-Hodgkin lymphoma or Hodgkin lymphoma was not increased among MGUS relatives. Among first-degree relatives of a nationwide MGUS cohort, we found elevated risks of MGUS, MM, LPL/WM, and CLL, supporting a role for germline susceptibility genes, shared environmental influences, or an interaction between both.

Viruses and thyroiditis: an update

Viral infections are frequently cited as a major environmental factor involved in subacute thyroiditis and autoimmune thyroid diseases This review examines the data related to the role of viruses in the development of thyroiditis.

Our research has been focused on human data. We have reviewed virological data for each type of thyroiditis at different levels of evidence; epidemiological data, serological data or research on circulating viruses, direct evidence of thyroid tissue infection. Interpretation of epidemiological and serological data must be cautious as they don't prove that this pathogen is responsible for the disease. However, direct evidence of the presence of viruses or their components in the organ are available for retroviruses (HFV) and mumps in subacute thyroiditis, for retroviruses (HTLV-1, HFV, HIV and SV40) in Graves's disease and for HTLV-1, enterovirus, rubella, mumps virus, HSV, EBV and parvovirus in Hashimoto's thyroiditis. However, it remains to determine whether they are responsible for thyroid diseases or whether they are just innocent bystanders. Further studies are needed to clarify the relationship between viruses and thyroid diseases, in order to develop new strategies for prevention and/or treatment.

Risk of hepatobiliary and pancreatic cancers after hepatitis C virus infection: A population-based study of U.S. veterans

Hepatitis C virus (HCV) may increase the risk of hepatopancreaticobiliary tumors other than hepatocellular carcinoma (HCC). Previous case control studies indicated a possible association between HCV and intrahepatic cholangiocarcinoma (ICC). Little is known about the association between HCV and extrahepatic cholangiocarcinoma (ECC) or pancreatic cancer. We conducted a cohort study including 146,394 HCV-infected and 572,293 HCV-uninfected patients who received care at Veterans Affairs health care facilities. Patients with two visits between 1996 and 2004 with HCV infection were included, as were up to four matched HCV-uninfected subjects for each HCV-infected subject. Risks of ICC, ECC, pancreatic cancer, and HCC were assessed using proportional hazards regression. In the 1.37 million person-years of follow-up, which began 6 months after the baseline visit, there were 75 cases of ECC, 37 cases of ICC, 617 cases of pancreatic cancer, and 1679 cases of HCC. As expected, the risk of HCC associated with HCV was very high (hazard ratio [HR], 15.09; 95% confidence interval [95% CI], 13.44, 16.94). Risk for ICC was elevated with HCV infection 2.55; 1.31, 4.95), but risk for ECC was not significantly increased (1.50; 0.60, 1.85). Adjustments for cirrhosis, diabetes, inflammatory bowel disease, hepatitis B, alcoholism, and alcoholic liver disease did not reduce the risk for ICC below twofold. The risk of pancreatic cancer was slightly elevated (1.23; 1.02, 1.49), but was attenuated after adjusting for alcohol use, pancreatitis, and other variables.

CONCLUSIONS

Findings indicated that HCV infection conferred a more than twofold elevated risk of ICC. Absence of an association with ECC was consistent in adjusted and unadjusted models. A significant association with pancreatic cancer was erased by alcohol use and other variables.

Infectious aetiology of Hodgkin and non-Hodgkin lymphomas: a review of the epidemiological evidence

Lymphomas constitute a heterogeneous group of malignant disorders with different clinical behaviours, pathological features and epidemiological characteristics. For some lymphoma subtypes, epidemiological evidence has long pointed to infectious aetiologies. A subset of Hodgkin lymphoma is strongly linked to Epstein-Barr virus (EBV) infection. In addition, infectious agents can directly infect and transform lymphocytes (e.g. EBV, human herpesvirus 8), induce immunosuppression (human immunodeficiency virus), or cause chronic immune stimulation (hepatitis C virus, Helicobacter pylori), all of which may play a role in the development of various non-Hodgkin lymphoma subtypes. Here, we review the epidemiological evidence linking infections with malignant lymphoma.

Hematopoietic malignancies associated with viral and alcoholic hepatitis

Hepatitis C virus (HCV) and hepatitis B virus (HBV) have been associated with hematopoietic malignancies, but data for many subtypes are limited. From the U.S. Surveillance, Epidemiology, and End Results-Medicare database, we selected 61,464 cases (> or = 67 years) with hematopoietic malignancies and 122,531 population-based controls, frequency-matched by gender, age, and year (1993--2002). Logistic regression was used to compare the prevalence of HCV, HBV, and alcoholic hepatitis in cases and controls, adjusted for matching factors, race, duration of Medicare coverage, and number of physician claims. HCV, HBV, and alcoholic hepatitis were reported in 195 (0.3%), 111 (0.2%), and 404 (0.7%) cases and 264 (0.2%), 242 (0.2%), and 798 (0.7%) controls, respectively. HCV was associated with increased risk of diffuse large B-cell lymphoma [odds ratio (OR) 1.52, 95% confidence interval (95% CI) 1.05-2.18], Burkitt lymphoma (OR 5.21, 95% CI 1.62-16.8), follicular lymphoma (OR 1.88, 95% CI 1.17-3.02), marginal zone lymphoma (OR 2.20, 95% CI 1.22-3.95), and acute myeloid leukemia (OR 1.54, 95% CI 1.00-2.37). In contrast, HBV was unrelated to any hematopoietic malignancies. Alcoholic hepatitis was associated with decreased risk of non-Hodgkin lymphoma overall, but increased risk of Burkitt lymphoma. In summary, HCV, but not other causes of hepatitis, was associated with the elevated risk of non-Hodgkin lymphoma and acute myeloid leukemia. HCV may induce lymphoproliferative malignancies through chronic immune stimulation.

Chronic immune stimulation and subsequent Waldenström macroglobulinemia

BACKGROUND

Certain autoimmune and infectious conditions are associated with increased risks of subtypes of non-Hodgkin lymphoma. A few previous studies suggest that chronic inflammation may particularly elevate risk of the distinct non-Hodgkin lymphoma subtype Waldenström macroglobulinemia (WM).

METHODS

We assessed WM risk in relation to a variety of chronic immune stimulatory conditions in 4 million US veterans. We identified 361 patients with WM with up to 27 years of follow-up. Using time-dependent Poisson regression, we estimated rate ratios (RRs) and 95% confidence intervals (CIs) for WM risk in relation to history of autoimmune diseases that typically have autoantibodies (with systemic or organ involvement) or do not have autoantibodies, infections, and allergies. All the models were adjusted for attained age, calendar year, race, number of hospital visits, and latency between study entry and exit.

RESULTS

The age-standardized incidence of WM was 0.34 per 100,000 person-years. Risk of WM was elevated in individuals with any previous autoimmune condition (RR, 2.23; 95% CI, 1.68-2.97), autoantibodies with systemic involvement (2.50; 1.55-4.02), or autoantibodies with organ involvement (2.30; 1.57-3.37). Risks of WM were also increased with hepatitis (RR, 3.39; 95% CI, 1.38-8.30), human immunodeficiency virus (12.05; 2.83-51.46), and rickettsiosis (3.35; 1.38-8.14).

CONCLUSIONS

In the largest investigation of WM risk factors to date, we found a 2- to 3-fold elevated risk of WM in persons with a personal history of autoimmune diseases with autoantibodies and notably elevated risks associated with hepatitis, human immunodeficiency virus, and rickettsiosis. These findings provide novel insights into the still unknown etiology of WM.

Prevalence of hepatitis B and C viruses in patients with lymphoproliferative disorders

The etiology of most lymphoproliferative disorders remains unclear, though several hypotheses have been proposed. One of the conjectured mechanisms is infection of a tumor clone by an oncologic virus. Recently, evidence has arisen implicating both hepatitis B and, even more so, hepatitis C viruses in the pathogenesis of lymphoproliferative disease. Based on this information, we surveyed the prevalence of hepatitis B and C virus in patients with lymphoproliferative disease. A total of 334 newly-diagnosed lymphoproliferative disease patients (200 males, 134 females) and 1,014 (133 females, 881 males) healthy controls were randomly recruited from the university blood bank. Serologic evaluation for hepatitis B and C viruses was conducted and confirmed using PCR analyses. Those with hepatitis B and/or C, controls, and subgroups of patients with lymphoproliferative disease were compared using Pearson Chi-square analysis. Among patients with lymphoid tumors, the seropositivity of HbsAg and/or anti-HCV was 8.7% (29/334), and among the controls 6.1% (49/802), however this difference did not achieve statistical significance (P = 0.23, OR: 1.36, 95% CI: 0.82-2.26). We found no significant gender- or age-related differences for either hepatitis B or C seropositivity. There were no significant differences between the seropositivity rates of hepatitis B, C, or both in either NHL or Hodgkin's lymphoma. However, in the diffuse large cell lymphoma and follicular lymphoma subgroups, the HbsAg seropositivity rate was significantly higher than that in the controls (P = 0.017, P = 0.048, respectively), as was the seropositivity rate for hepatitis C in those with diffuse B cell lymphoma versus controls (P = 0.008). We did not identify any significant difference in the combined prevalence of hepatitis B or C seropositivity between patients with lymphoproliferative disorders and controls. However, significant differences were revealed among certain patient subgroups versus the controls. These two viruses could play a role in the development of certain specific lymphoproliferative disorders. Nevertheless, larger epidemiological studies are necessary and should focus, particularly on specific patient subgroups.

A case of primary hepatic non-Hodgkin's lymphoma with chronic hepatitis C

We report a case of primary hepatic non-Hodgkin's lymphoma in a 67-year-old man with chronic hepatitis C. Laboratory data revealed slightly elevated liver function parameters and positive for hepatitis C virus (HCV) antibody. Abdominal ultrasonography showed hypoechoic lesions approximately 5 mm in diameter in the whole liver. Magnetic resonance imaging showed that the tumors were isointense in relationship to the liver on T(1)-weighted images but were slightly hyperintense on T(2)-weighted images. Under a clinical diagnosis of liver tumor, liver biopsy was performed. Histological examination confirmed a diagnosis of non-Hodgkin's diffuse large B-cell lymphoma, and the immunophenotype was identified to be the germinal cell type.

Risk of lymphoproliferative disorders among first-degree relatives of lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia patients: a population-based study in Sweden

A role for genetic factors in the etiology of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM) is implicated based on prior findings from multiply affected families and small case-control and cohort studies. We identified 2144 LPL/WM patients (1539 WM [72%] and 605 LPL [28%]) diagnosed in Sweden, 8279 population-based matched controls, and linkable first-degree relatives of patients (n = 6177) and controls (n = 24 609). Using a marginal survival model, we calculated relative risks and 95% confidence intervals as measures of familial aggregation. We found first-degree relatives of LPL/WM patients to have 20-fold (4.1-98.4), 3.0-fold (2.0-4.4), 3.4-fold (1.7-6.6), and 5.0-fold (1.3-18.9) increased risks of developing LPL/WM, non-Hodgkin lymphoma (NHL), chronic lymphocytic leukemia (CLL), and monoclonal gammopathy of undetermined significance (MGUS), respectively. However, there was no evidence of an increased risk of developing multiple myeloma or Hodgkin lymphoma. In analyses stratified by type of first-degree relative (parent, sibling, offspring), age at diagnosis of the probands (greater or less than 70 years), and sex of the first-degree relative, we did not observe the risk estimates to be significantly different compared with the overall analyses. Our findings of highly increased risks of developing LPL/WM, NHL, CLL, and MGUS support the operation of shared susceptibility genes that predispose to LPL/WM and other lymphoproliferative disorders.

Immune responses during acute and chronic infection with hepatitis C virus

Hepatitis C virus (HCV) induces persistent infection and causes chronic liver disease in most infected patients. Vigorous HCV-specific CD4+ and CD8+ T cell responses against HCV multiple epitopes are necessary for spontaneous viral clearance during the acute phase, but the virus appears to have multiple strategies to evade these defenses. There are relatively few studies on the role of immune responses during the chronic phase of infection. CD4+ T cell responses appear to protect against liver injury and may be important to clearance during interferon and ribavirin based therapy. Classic cytotoxic T cells (CTL) may primarily damage the liver in chronic HCV, but there may be subpopulations of T cells that protect against liver inflammation. Resolution of these outstanding questions is important to the development of a prophylactic vaccine as well as improving therapeutic options for those with chronic infection.

High prevalence of occult hepatitis B virus infection in patients with B cell non-Hodgkin's lymphoma

Several reports recently found that patients with B cell non-Hodgkin's lymphoma (NHL) had a higher carrier rate of hepatitis B surface antigen (HBsAg). The current study aimed to examine the hepatitis B virus (HBV) infection status of NHL patients in Taiwan, an HBV-endemic area. Serum HBV and serum hepatitis C virus were measured in 471 NHL patients and 1,013 non-lymphoma cancer patients enrolled between February 2000 and March 2007. Furthermore, nested polymerase chain reaction of HBV-DNA was used to examine the sera from selected patients in these two populations and healthy volunteers for the presence of occult HBV infection. The infection rates (as indicated by the rates of HBsAg and occult HBV) were compared between different groups. There was a higher incidence of HBV infection in B cell NHL patients (23.5%), especially patients with diffuse large B lymphoma, than solid tumor patients (15.6%, P = 0.001). Among HbsAg-negative patients, those with B cell NHL had a higher prevalence of occult HBV infection (6%) than those with non-lymphoma solid tumors and healthy volunteers, 0% and 0.9%, respectively (P = 0.005). B cell NHL patients, even HBsAg-negative B cell NHL patients, but not T cell NHL patients, have a higher incidence of HBV infection than patients with solid tumors. Our findings support the etiologic role of HBV infection in B cell NHL.

Hepatitis C and non-Hodgkin lymphoma among 4784 cases and 6269 controls from the International Lymphoma Epidemiology Consortium

BACKGROUND & AIMS

Increasing evidence points towards a role of hepatitis C virus (HCV) infection in causing malignant lymphomas. We pooled case-control study data to provide robust estimates of the risk of non-Hodgkin's lymphoma (NHL) subtypes after HCV infection.

METHODS

The analysis included 7 member studies from the International Lymphoma Epidemiology Consortium (InterLymph) based in Europe, North America, and Australia. Adult cases of NHL (n = 4784) were diagnosed between 1988 and 2004 and controls (n = 6269) were matched by age, sex, and study center. All studies used third-generation enzyme-linked immunosorbent assays to test for antibodies against HCV in serum samples. Participants who were human immunodeficiency virus positive or were organ-transplant recipients were excluded.

RESULTS

HCV infection was detected in 172 NHL cases (3.60%) and in 169 (2.70%) controls (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.40-2.25). In subtype-specific analyses, HCV prevalence was associated with marginal zone lymphoma (OR, 2.47; 95% CI, 1.44-4.23), diffuse large B-cell lymphoma (OR, 2.24; 95% CI, 1.68-2.99), and lymphoplasmacytic lymphoma (OR, 2.57; 95% CI, 1.14-5.79). Notably, risk estimates were not increased for follicular lymphoma (OR, 1.02; 95% CI, 0.65-1.60).

CONCLUSIONS

These results confirm the association between HCV infection and NHL and specific B-NHL subtypes (diffuse large B-cell lymphoma, marginal zone lymphoma, and lymphoplasmacytic lymphoma).

Understanding microbe-induced cancers

Microbes are important causes of human cancers, and our estimation of their significance continues to grow as cancer biology is better dissected. A classification system is proposed that highlights common and proposed microbe-induced pathways toward oncogenesis, with an emphasis on types of targeted cells and host-microbial interactions. The central principles that underlie oncogenesis induced by the many diverse microbes and the major mechanisms involved are outlined. The phenomenon of microbe-induced cancers raises a number of important biological questions, the solving of which may inform other fields, including aging and degenerative disorders. Finally, our challenge for the future is to better understand the steps in microbe-induced cancers to optimize both prevention and therapy.

Hepatitis C infection and risk of malignant lymphoma

The association between hepatitis C virus (HCV) infection and risk of malignant lymphoma remains controversial, perhaps due to small-sized studies and low prevalence of HCV in the general population. On the basis of a large Danish-Swedish population-based case-control study, 2,819 lymphoma patients and 1,856 controls of second-generation Danish-Swedish origin were screened for HCV infection using an enzyme-linked immunosorbent assay and a confirming recombinant immunoblot assay (RIBA) test. Positive samples were tested with real-time PCR for the presence of HCV RNA. The association between HCV infection and risk of malignant lymphoma was assessed by logistic regression. When intermediate RIBA test results were interpreted as positive, anti-HCV antibody positivity was associated with a nonsignificant increased risk of non-Hodgkin lymphoma (NHL) overall (odds ratio (OR) = 2.2; 95% confidence interval (CI) 0.9-5.3; n = 20 cases), of B-cell lymphomas combined (OR = 2.4 [1.0-5.8]; n = 20) and of lymphoplasmacytic lymphoma (OR = 5.2 [1.0-26.4]; n = 2). No patients with T-cell or Hodgkin lymphoma were HCV-positive. A more conservative definition of HCV positivity (disregarding intermediate RIBA results) resulted in an OR = 1.6 (0.3-8.5; n = 5) for NHL overall. When the definition was further restricted to require HCV RNA positivity, OR was 1.7 (0.2-16.2; n = 3) for NHL overall. Our findings from a population with a low prevalence of HCV suggest a positive association between HCV and risk of NHL, in particular of B-cell origin.

Clonal expansion of immunoglobulin M+CD27+ B cells in HCV-associated mixed cryoglobulinemia

Hepatitis C virus (HCV) is associated with B-cell lymphoproliferative disorders such as mixed cryoglobulinemia (MC) and B-cell non-Hodgkin lymphoma (B-NHL). The pathogenesis of these disorders remains unclear, and it has been proposed that HCV drives the pro-liferation of B cells. Here we demonstrate that certain HCV(+)MC(+) subjects have clonal expansions of immunoglobulin M (IgM)(+)kappa(+)IgD(low/-)CD21(low)CD27(+) B cells. Using RT-PCR to amplify Ig from these singly sorted cells, we show that these predominantly rheumatoid factor-encoding V(H)1-69/J(H)4 and V(kappa)3-20 gene segment-restricted cells have low to moderate levels of somatic hypermutations. Ig sequence analysis suggests that antigen selection drives the generation of mutated clones. These findings lend further support to the notion that specific antigenic stimulation leads to B-cell proliferation in HCV MC and that chronic B-cell stimulation may set the stage for malignant transformation and the development of B-NHL. The finding that these hypermutated, marginal zone-like IgM(+)CD27(+) B cells are clonally expanded in certain subjects with MC offers insight into mechanisms of HCV-associated MC and B-cell malignancy. This study was registered at www.clinicaltrials.gov as NCT00219999.

Risk of multiple myeloma and monoclonal gammopathy of undetermined significance among white and black male United States veterans with prior autoimmune, infectious, inflammatory, and allergic disorders

In a retrospective cohort of more than 4 million white and black male United States (US) veterans, we explored the role of specific prior autoimmune, infectious, inflammatory, and allergic disorders in the etiology of multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS). Patients were selected from computerized inpatient discharge records at US Veterans Affairs hospitals. The analysis included 4641 patients (3040 white, 1601 black) and 2046 patients (1312 white; 734 black) with a discharge diagnosis of MM and MGUS, respectively. Using Poisson regression, we calculated age-adjusted relative risks (RRs) and 95% confidence intervals (CIs) for the relationship between MM, MGUS, and specific prior medical conditions. Significantly elevated risks of MM were associated with broad categories of autoimmune (RR, 1.15; 95% CI, 1.02-1.28), infectious (RR, 1.29; 95% CI, 1.20-1.38), and inflammatory disorders (RR, 1.18; 95% CI, 1.10-1.27) and specific prior autoimmune (polymyositis/dermatomyositis, systemic sclerosis, autoimmune hemolytic anemia, pernicious anemia, and ankylosing spondylitis), infectious (pneumonia, hepatitis, meningitis, septicemia, herpes zoster, and poliomyelitis), and inflammatory (glomerulonephritis, nephrotic syndrome, and osteoarthritis) disorders. Risks for MGUS were generally of similar magnitude. Our results indicate that various types of immune-mediated conditions might act as triggers for MM/MGUS development.

Liver dysfunction after chemotherapy in lymphoma patients infected with hepatitis C

Reactivation of hepatitis B virus (HBV) infection in asymptomatic hepatitis B surface antigen carriers undergoing chemotherapy or immunosuppressive therapy is a well-documented complication. However, data on the consequence of chemotherapy on the course of hepatitis C virus (HCV) infection in HCV+ patients have been controversial. Here, we review the current knowledge about the complications related to HCV in lymphoma patients receiving chemotherapy/immunosuppressive therapy. Although less frequent than HBV, these complications occur in a subset of patients with mortality rates up to 45%. Therefore, baseline screening for HBV and HCV before initiation of chemotherapy is crucial. High-risk patients having chronic active hepatitis, high baseline HCV viral load, HBV co-infection and receiving cytotoxic drugs, corticosteroids and rituximab (particularly if combined) should be closely monitored for serum transaminase, bilirubin and HCV RNA levels.

Prevalence of monoclonal gammopathy of undetermined significance among men in Ghana

OBJECTIVE

To determine the prevalence of monoclonal gammopathy of undetermined significance (MGUS), a precursor of multiple myeloma (MM), in Ghanaian men vs white men and to test for evidence to support an underlying race-related predisposition of the 2-fold higher prevalence of MGUS in African Americans vs whites.

PARTICIPANTS AND METHODS

Between September 1, 2004, and September 30, 2006, 917 men (50-74 years) underwent in-person interviews and physical examinations. Serum samples from all participants were analyzed by electrophoresis performed on agarose gel; any serum sample with a discrete or localized band was subjected to immunofixation. Age-adjusted and standardized (to the 2000 world population) prevalence estimates of MGUS and 95% confidence intervals (CIs) were computed in the Ghanaian men and compared with MGUS prevalence in 7996 white men from Minnesota. Associations between selected characteristics and MGUS prevalence were assessed by the Fisher exact test and logistic regression models.

RESULTS

Of the 917 study participants, 54 were found to have MGUS, yielding an age-adjusted prevalence of 5.84 (95% CI, 4.27-7.40) per 100 persons. No significant variation was found by age group, ethnicity, education status, or prior infectious diseases. The concentration of monoclonal immunoglobulin was undetectable in 41 (76%) of the 54 MGUS cases, less than 1 g/dL in 10 patients (19%), and 1 g/dL or more in only 3 patients (6%). Compared with white men, the age-adjusted prevalence of MGUS was 1.97-fold (95% CI, 1.94-2.00) higher in Ghanaian men.

CONCLUSION

The prevalence of MGUS in Ghanaian men was twice that in white men, supporting the hypothesis that race-related genetic susceptibility could explain the higher rates of MGUS in black populations. An improved understanding of MGUS and MM pathophysiology would facilitate the development of strategies to prevent progression of MGUS to MM.

Hepatitis C virus and lymphoma

Hepatitis C virus (HCV) is well known for its aetiological role in chronic non-A, non-B viral hepatitis, liver cirrhosis and hepatocellular carcinoma; in addition, the virus has also been implicated in a number of extra-hepatic "autoimmune" disease manifestations. A causative association between HCV and non-Hodgkin lymphoma (NHL) was postulated relatively recently and has been the subject of intense investigation, as well as some debate. On the strength of epidemiological data, emerging biological investigations and clinical observations, HCV appears to be involved in the pathogenesis of at least a proportion of patients with NHL. Morphologically, HCV-associated lymphomas represent a variety of histological subtypes including marginal zone lymphoma (splenic, nodal and extranodal), small lymphocytic lymphoma/chronic lymphocytic leukaemia, lymphoplasmacytic lymphoma and diffuse large B-cell lymphoma. Remarkably, some HCV-associated NHL appears to be highly responsive to antiviral therapy, providing some clinical evidence for this relationship, as well as the prospect for novel therapeutic intervention.

Hepatitis C virus infection and risk of posttransplantation lymphoproliferative disorder among solid organ transplant recipients

Posttransplantation lymphoproliferative disorder (PTLD) is a serious complication of solid organ transplantation. Hepatitis C virus (HCV) infection has been linked to increased risk of lymphoma among immunocompetent individuals. We therefore investigated the association between HCV infection and PTLD in a retrospective cohort study of all individuals in the United States who received their first solid organ transplant from 1994 to 2005 (N = 210 763) using Scientific Registry of Transplant Recipients data. During follow-up, 1630 patients with PTLD were diagnosed. HCV prevalence at transplantation was 11.3%. HCV infection did not increase PTLD risk in the total cohort (Cox regression model, hazard ratio [HR] = 0.84; 95% confidence interval [CI] 0.68-1.05), even after adjustment for type of organ transplanted, indication for transplantation, degree of HLA mismatch, donor type, or use of immunosuppression medications. Additional analyses also revealed no association by PTLD subtype (defined by site, pathology, cell type, and tumor Epstein-Barr virus [EBV] status). HCV infection did increase PTLD risk among the 2.8% of patients (N = 5959) who were not reported to have received immunosuppression maintenance medications prior to hospital discharge (HR = 3.09; 95% CI, 1.14-8.42; P interaction = .007). Our findings suggest that HCV is not a major risk factor for PTLD, which is consistent with the model in which an intact immune system is necessary for development of HCV-related lymphoproliferation.