Oligoclonal non-neoplastic B cell expansion is the key feature of type II mixed cryoglobulinemia: clinical and molecular findings do not support a bone marrow pathologic diagnosis of indolent B cell lymphoma

OBJECTIVE

Type II mixed cryoglobulinemia (type II MC) is often characterized by features of indolent B cell lymphoma (IBCL) found on pathologic examination of bone marrow, whereas the clinical evidence does not indicate a neoplastic disorder. To better address the issue of indolent malignant versus nonmalignant bone marrow lymphoproliferation underlying type II MC, molecular analyses of B cell clonality were performed in the present study, in conjunction with clinical and pathologic characterization.

METHODS

Polymerase chain reaction DNA amplification of immunoglobulin heavy chain genes was performed in bone marrow biopsy specimens obtained from 15 selected patients with type II MC, all infected with hepatitis C virus. Five of them had also developed overt B cell lymphoma (OBCL) during followup. Bone marrow features were consistent with IBCL in 9 of the 15 patients (group 1) and with reactive lymphoplasmacytosis in 6 of the 15 (group 2).

RESULTS

An oligoclonal B cell expansion was detected in 6 of 9 baseline bone marrow lesions from group 1 patients (biclonal or monoclonal expansion in the remaining 3 cases), and in 6 of 6 from group 2 patients. OBCL was always monoclonal. Selected lesions were analyzed by clonospecific hybridization and by cloning and sequence analysis in patients who had developed OBCL at followup. In 4 of 5 cases, OBCL did not originate from the dominant B cell clones that were overexpanded in the putative neoplastic baseline bone marrow lesions. OBCL clones showed significant homology with rheumatoid factor database sequences.

CONCLUSION

Based on the present results, as well as on evidence from previous studies of liver lesions, oligoclonal non-neoplastic B cell proliferation in the course of chronic infection-related inflammation appears to be the key feature of type II MC. Of note, molecular evidence from target tissues supports the clinical findings both at the time of type II MC diagnosis and in cases of OBCL complication. Bone marrow pathologic findings resembling those of IBCL should thus be considered in the light of clinical and molecular evidence.

Hepatic lymphoid aggregates in chronic hepatitis C and mixed cryoglobulinemia

We have examined the clinical (virological and immunological), histological and immunohistochemical features of liver lymphoid nodules in hepatitis C virus-positive (HCV+)/mixed cryoglobulinemia (type II and III) and chronic hepatitis C. The clinical features of liver disease were found to be similar in all patients. In all these groups, liver lymphoid nodules were observed to a similar extent, being more frequent in earlier phases of liver disease and less in more advanced stages. These data were confirmed by studies in serial biopsy samples taken from individual patients with type II mixed cryoglobulinemia; the loss of lymphoid nodules with progression to more advanced histological stages of disease in these patients was accompanied by a decrease of the serum levels of cryoglobulins (although not statistically significant). By immunohistochemical analysis, the liver lymphoid nodules contained predominantly B cells with a CD5+/bcl2+/Ki67- phenotype, which were always polyclonal in type III mixed cryoglobulinemia and chronic hepatitis C, and monoclonal in type II mixed cryoglobulinemia. These immunological features were consistent with an active role of the immune system in HCV-associated liver necro-inflammation. Only in type II mixed cryoglobulinemia was there a clonal restriction of B cells. The immunological profile (autoantibodies) and viral genotypes were examined in some patients, but no significant correlation with clinical and immunohistochemical findings was found; however, the prevalence of genotype 2a was significantly higher in type II mixed cryoglobulinemia than in type III and chronic hepatitis without cryoglobulinemia.

High prevalence of hepatitis C virus (HCV) genotype 2 in Italian patients with chronic liver disease

The prevalence of different genotypes of Hepatitis C virus may vary between geographic areas and it is possible that various genotypes have different pathogenic characteristics. Therefore, 90 consecutive Italian patients anti-Hepatitis C Virus positive with a broad spectrum of chronic liver disease, have been analysed to observe prevalence of various genotypes of Hepatitis C Virus. Genotyping was performed by polymerase chain reaction with a set of nested biotinylated primers, located in 5'UTR region. Genotype 1b and genotype 2a were the most commonly encountered (respectively, 50% and 37%) whereas other genotypes were rare. The unexpected high prevalence of genotype 2a allowed direct comparison of clinical characteristics and response to therapy between patients with genotype 2a and those with 1b. Genotype 1b was more prevalent than 2a in patients over 60 years (29 vs 12) and in those with more severe liver disease (34 vs 16). In a univariate analysis, genotype 2a was associated with less severe liver disease (p = 0.02) and younger age (p = 0.018), in comparison with genotype 1b. Patients with genotype 2a responded to interferon alpha therapy better than those with 1b (p = 0.007). In a multivariate analysis, only younger age was associated with genotype 2a. Genotype 2a (in comparison with 1b) and absence of cirrhosis were independent predictors of response to interferon alpha. In conclusion, genotype 2a is playing an emerging role in younger Italian patients and seems more sensitive than 1b to interferon alpha therapy.

Bone marrow findings further support the hypothesis that essential mixed cryoglobulinemia type II is characterized by a monoclonal B-cell proliferation

One-hundred-sixteen consecutive bone-marrow biopsies were taken from 76 patients with essential mixed cryoglobulinemia type II (type II cryo), whose median follow-up was 97 months. Fifty-four out of fifty-six subjects who underwent ELISA and RIBA tests for HCV, were found to be positive. At conventional light microscopic examination, 64/76 patients showed discrete lymphoid infiltrates consisting of small elements with plasmacytoid differentiation and with frequent paratrabecular location. Thirty-nine biopsies were studied by immunohistochemistry that revealed the B-cell nature of the infiltrates (CD20+, CD45RA+, CD79 alpha+, CD3-, CD45RO-), with demonstrable monotypic Ig light-chain restriction in 22 cases. It is worthy of note that the lymphoid elements usually appeared protected against apoptosis, because of the strong expression of the bcl-2 oncogene product, and provided with a very low proliferative capacity, the Ki-67 index being lower that 3%. The latter findings are in keeping with the indolent behaviour of the clonal lymphoid population observed in type II cryo and allow some speculation as to the need for environmental stimuli for its maintenance as well as further mutagenic events for its eventual transformation into an overt lymphoma.

Lymphoproliferation in type II mixed cryoglobulinemia

OBJECTIVE

The role of the hepatitis C virus (HCV) in the etiology of type II mixed cryoglobulinemia (MC) has been well established, but the pathogenetical relationships among the virus, the immune system, the natural history of MC, and lymphoproliferation in the bone marrow and liver need to be further elucidated.

METHODS

Eighty-two patients with HCV positive type II MC and 20 subjects with chronic hepatitis C without MC were studied: bone marrow and liver specimens were examined by routine histology and immunohistochemistry, particularly focusing on parameters related to disease behaviour, such as the expression of the bcl-2 oncogene product and the proliferation-associated Ki67 antigen.

RESULTS

In most MC patients there were lymphoid infiltrates within the bone marrow showing a monomorphic cytology, frequent immunoglobulin light chain monotypic restriction, expression of the anti-apoptotic bcl-2 oncogene product, and a low proliferative capacity (Ki-67 < 3%). On the other hand, in all non-cryoglobulinemic patients a bone marrow picture of reactive lymphoplasmacytosis was found. In both MC and chronic hepatitis patients, the liver biopsy showed portal infiltrates consisting of T-cells, associated with a significant B-cell component; the latter was particularly abundant in MC, where it was frequently arranged in pseudo-follicles. The B-cell component expressed the bcl-2 oncogene product and CD5 antigen, thus suggesting that the immune system is actively involved in the production of liver damage both in MC and non-cryoglobulinemic patients. It is worth noting that in MC patients (but not in the non-cryoglobulinemic patients) these CD5+/bcl-2+ B-cells frequently also exhibited a monotypic restriction bearing an IgM kappa.

CONCLUSION

Our findings in these liver and bone marrow studies further support the role of a lymphoproliferative disorder in the pathology of type II MC: the B cells involved accumulate due to the inhibition of apoptosis, and their low proliferative index justifies the indolent course of the disease. HCV probably interacts with these B-cells, facilitating their clonal expansion.

A pilot study on the effectiveness of cyclosporine in type II mixed cryoglobulinemia

OBJECTIVE

To evaluate the effect of cyclosporine in the treatment of type II mixed cryoglobulinemia, after the failure of more conventional therapies.

METHODS

Two patients with type II mixed cryoglobulinemia associated with chronic HCV infection, purpura, liver disease, and sensitive/motor neuropathy were treated with cyclosporine (2.5 mg/Kg/b.w.), after their failure to respond to treatment with corticosteroid, immunosuppressive drugs, interferon, and plasmapheresis.

RESULTS

In both patients an improvement in the clinical manifestations (purpura and peripheral neuropathy), laboratory results (serum transaminases and cryocrit), and liver histology was seen, as well as the disappearance of bone marrow B-cell lymphoproliferation.

CONCLUSION

Cyclosporine may be useful in the treatment of type II mixed cryoglobulinemia with prominent autoimmune clinical manifestations, although further studies are needed to better define the selection of patients.

[Anti-GOR antibodies in type II mixed cryoglobulinemia associated with hepatitis C virus infection]

The frequent association of chronic hepatitic C virus (HCV) infection and type II mixed cryoglobulinemia is considered to be one of the possible signs of interaction between the virus and the immune system. This could also be the case for the appearance of anti-GOR antibodies in serum, as they react with both viral and host antigens. We studied a group of patients with chronic hepatitis C infection and a group with type II mixed cryoglobulinemia associated with HCV infection to ascertain if anti-GOR or other non-organ specific autoantibodies were present in the serum. We found no significant difference between the two groups in presence, prevalence or titer of anti-GOR or other autoantibodies. Moreover, the expression of anti-GOR does not seem to influence the severity of liver damage. Our data support the hypothesis that anti-GOR antibodies are a simple expression of molecular mimicry between viral and human epitopes.

[A sustained response in chronic hepatitis C treated with interferon]

We analyzed 27 subjects with long-term response, from a group of 110 interferon treated patients with biopsy-proven chronic hepatitis and serum anti-HCV antibodies. The following variables were assessed as potential predictors: sex, age, ALT level before the therapy was started, liver structure, type of interferon, total amount of interferon. Total amount of administered interferon statistically correlated with long-term response by univariate analysis. Nevertheless upon stepwise logistic multivariate analysis none of them was independently predictive of long-term response. Additional studies would be needed in order to develop a model capable of predicting from pre-treatment features which patients are likely to have long-term response.

Reliability of immunoassays for anti-HCV antibodies (ELISA and RIBA II) in patients with essential mixed cryoglobulinemia (EMC)

The recent reports of a very high frequency of signs of hepatitis C virus (HCV) infection among patients with essential mixed cryoglobulins (EMC) suggest new hypotheses for the pathogenesis of this disease. However, most of these studies have been seriously criticized. The serologic test designed for detection of anti-HCV antibodies (ELISA, RIBA I and II) may yield a significant rate of false-positive results when performed on cryoglobulinemic sera, and the detection of the HCV genome by PCR is still heavily conditioned by practical problems. Indirect, but possibly more reliable, evidence of HCV infection in cryoglobulinemic patients might come from the demonstration of anti-HCV antibodies by a conventional technique (ELISA or RIBA) in the purified polyclonal non-rheumatoid immunoglobulinemic fraction excreted in the urine by glomerular filtration. Fifty-two patients whose serum had tested positive for HCV antibodies (by ELISA and RIBA) on multiple occasions were enrolled in this study. They were diagnosed as having either EMC or HCV chronic hepatitis without cryoglobulinemia at least one year ago. The urine samples of these patients were tested for anti-HCV antibodies by ELISA and RIBA. In patients with chronic C hepatitis the antibodies most frequently found in the serum were anti-C33c and anti-C22-3. The results of the RIBA were substantially confirmed by ELISA, with a positive test in the urine of 30 of 32 seropositive patients. Similar results were obtained in patients with EMC II. We conclude that the specificity of the RIBA and ELISA tests for HCV antibodies in patients with EMC appears to be as high as in HCV+ patients without serum cryoglobulins. EMC patients have a high incidence of HCV infection and active chronic liver disease.

Hepatotoxicity of hydroxy-methyl-glutaryl-coenzyme A reductase inhibitors

The first clinical studies on hydroxy-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors reported a low incidence of liver toxicity. The personal observation of a case of simvastatin-induced acute cholestatic hepatitis prompted us to evaluate the true incidence of hepatic side effects of these drugs in a large Italian population. One hundred patients taking simvastatin and ninety patients treated with pravastatin were followed-up six months with periodical evaluation of serum lipid levels and liver function test. In 5% of simvastatin-treated patients and 4.5% of pravastatin-treated patients significant liver toxicity was observed, which required drug discontinuation. The mechanism of liver damage was direct, idiosyncratic, but immunological features of drug toxicity could be hypothesized in one patient.

Combined evaluation of total and functional liver plasma flows and intrahepatic shunting

A diagnostic protocol was studied, designed to evaluate the main parameters of liver circulation in man. A water solution of D-sorbitol (S) and indocyanine green (ICG) was infused intravenously in six controls and nine cirrhotics. Steady-state renal and hepatic S clearances as well as hepatic ICG clearance were calculated. In controls the values (mean +/- SD) of the independent measurements of S and ICG hepatic clearance were 978 +/- 107 and 519 +/- 142 ml/min, respectively, while in cirrhotic patients they were 554 +/- 238 and 231 +/- 90 ml/min. Owing to the kinetic properties of S, its hepatic clearance may be regarded as a measure of functional liver plasma flow (FLPF). The total liver plasma flow (TLPF) values (mean +/- SD), calculated according to Fick's principle, were 1091 +/- 157 ml/min (S method) and 1033 +/- 153 ml/min (ICG method) in controls, and 1251 +/- 554 and 1284 +/- 677 ml/min in cirrhotics. In controls, FLPF was found to be very close to TLPF. In cirrhotic patients the difference between TLPF and FLPF (ranging from 169 to 2093 ml/min when measured by S method) was considered as an approximate estimate of intrahepatic shunting. The procedure is safe and simple and may add a new dimension to the investigation of hepatic circulation.

Application of artificial intelligence techniques to a well defined clinical problem: jaundice diagnosis

Jaundice is a very common medical condition, in which pathophysiological knowledge has been quite well assessed and clinical features are usually well known. However, incorrect conclusions are sometimes reached in medical practice which can lead to serious implications. Thus, jaundice diagnosis appears as one of the medical situations which might be substantially improved by computer assistance. The present study is aimed at describing and discussing in what way a computer program supporting medical decision making in jaundiced patients can be developed on the basis of advanced Artificial Intelligence methods. To this extent methodological problems concerned with the organization and the formalization of medical knowledge have been outlined with some detail. The resulting expert system is expected to become a well assessed and potentially useful tool for both medical decision making and medical education.

D-sorbitol plasma disappearance rate: an index to evaluate changes in liver circulation

The hepatic clearance of D-sorbitol was proven to be a reliable parameter for evaluating the functional liver plasma flow. Twenty-five normal subjects and 50 cirrhotic patients were studied in order to assess if the measure of the plasma disappearance rate of sorbitol can be used as a simpler procedure to evaluate changes in liver perfusion and to predict modifications of drug bioavailability due to circulatory events. The plasma disappearance rate was calculated between 10 and 20 min after intravenous administration of a 2-g dose because in this time interval plasma levels were in the optimum range for the chemical assay, and the plasma concentration/time curve fitted a decreasing exponential function. Plasma disappearance rate values were found to correlate significantly (r = 0.666, p less than 0.001) with sorbitol hepatic clearance, as calculated after the 2-h test. The test had a good day-to-day reproducibility both in normal subjects and cirrhotic patients. In 5 patients submitted to surgical side-to-side portacaval shunt, decreases of plasma disappearance rate and sorbitol hepatic clearance showed no significant difference. Mean values (+/- SD) of D-sorbitol plasma disappearance rate were 0.048 +/- 0.014 min-1 in cirrhotic patients, and 0.081 +/- 0.014 min-1 in normal subjects (p less than 0.001).

Non-invasive evaluation of portal-systemic shunting in man by D-sorbitol bioavailability

Portal-systemic shunting is an important circulatory abnormality in patients with cirrhosis. This study explores the potential of the natural polyol D-sorbitol as test compound for non-invasive assessment of shunting. Ten normal subjects, 10 patients with cirrhosis and 12 cirrhotics with surgical portacaval shunts were studied after oral and intravenous administration of a 2 g dose of sorbitol. As measured by the H2 breath test, removal from the intestinal lumen was complete in both groups. Bioavailability of sorbitol, calculated as ratio of the areas under the plasma concentration/time curve after p.o. and i.v. administration, was zero in normal subjects, 0.29 +/- 0.15 in cirrhotic patients, and 0.38 +/- 0.11 in patients with portacaval shunts. Calculation of bioavailability on the basis of urinary outputs of sorbitol gave similar results. It is concluded that the bioavailability of sorbitol reflects portal-systemic shunting, although the relatively low figures suggest some degree of sorbitol metabolism by enterocytes.

Sorbitol clearance: a parameter reflecting liver plasma flow in the rat

According to the clearance concepts, the functional liver plasma flow may be directly measured from the plasma kinetics of any substance whose hepatic intrinsic clearance largely exceeds liver perfusion. The present study was designed to ascertain the requirements for the reliability of D-sorbitol plasma clearance in evaluating changes of liver perfusion in the male Wistar rat. The plasma disappearance curve of D-sorbitol (3 mg/100 g b.w. by bolus i.v. injection) followed a first order kinetics and fitted a two-compartment model. Very similar estimates of D-sorbitol plasma clearance were obtained by applying the area under the curve method to data obtained by the trapezoidal rule and by compartmental analysis. D-sorbitol hepatic extraction was almost complete in controls and in rats submitted to porta-caval shunt and hepatic artery ligation, while significantly decreased after partial hepatectomy. Renal output never exceeded 10% of the administered amount. No in-vivo diffusion into red cells was observed. In controls, the functional liver plasma flow, as measured by D-sorbitol clearance was 2.83 +/- 0.68 ml/min/100 g (mean +/- SD). Significantly lower values were found in rats submitted to porta-caval shunt (1.19 +/- 0.38), hepatic artery ligation (2.06 +/- 0.53), and partial hepatectomy (1.03 +/- 0.44).