Changes of IgG-bearing cell populations in the portal tracts of patients with chronic liver disease of viral etiology: an evaluation by immunoperoxidase method and computerized image analysis

[Characteristics of the hepatitis C virus and viral predictors of therapeutic response]

NATURAL HISTORY OF HEPATITIS C-INFECTION AND VIRAL CHARACTERISTICS: Hepatitis C-virus (HCV) infection is a major cause of non-A, non-B-hepatitis and, additionally, is associated with liver cirrhosis and hepato-cellular carcinoma. The high degree of chronificity of HCV-infection is reasonable due to antigenic variability of neutralizing epitopes leading to incomplete immunoresponse with subsequent virus persistence. Besides genetic variants of HCV within a virus population (quasispecies nature of HCV), different genotypes are classified being genetically and phenotypically distinct, and geographically restricted in part. Genotyping of HCV is not only important for phylogenetic and epidemiological studies, but also a predictive marker for pathogenesis and therapy. VIRAL PREDICTORS OF HCV THERAPY: In a meta-analysis of 18 therapeutical studies of chronical HCV infections, genotype 1 and high levels of viremia determined markedly the response to interferon therapy. In this context, clinical trials have proven the effect of a combined therapy with interferon and ribavirin. Especially patients with HCV genotype 1 or high levels of viremia had a real benefit from combined antiviral therapy in comparison to monotherapy with interferon. CONCLUSION AND FUTURE CONCEPTS: Besides recent concepts improving the therapeutical response to HCV infection, further effort is necessary to develop more successful strategies for eradication of hepatitis C virus. In this context, variations of interferon therapy should be evaluated (e.g. higher and daily doses, longer duration of interferon therapy, "retarded" interferon (PEG-IFN). In addition, new therapeutical concepts should be performed including a combination of interferon with other known antiviral agents (amantadine), a combination with immunomodulators (GM-CSF, thymosin alpha 1), the development of new antiviral agents (inhibitors of viral proteases, helicases and polymerases) and the exploration of anti-viral, molecular strategies (specific ribozymes, antisense oligonucleotides and DNA-vaccination). Nevertheless, the development of an effective vaccination should be the most important challenge for the future.

Interleukin-1-producing plasma cells in close contact with hepatocytes in patients with chronic active hepatitis

BACKGROUND/AIMS

In chronic active liver diseases (CALD) with viral aetiology, a population of plasma cells localised in the piecemeal necrosis areas was previously detected by means of autoradiography after in vitro 3H-proline incorporation, a method which proved much more sensitive than conventional immunohistochemical procedures. These plasma cells, characteristically located in niches among hepatocytes, in close contact with collagen fibrils, have been hypothesised to exert a role in fibrogenesis stimulation, and particularly in collagen synthesis, possibly through secretion of lymphokines. Specifically, we investigated the presence of interleukin-1, well known to play a crucial role in inflammation and production of collagen by epithelial cells, and to be present in activated plasma cells of myeloma.

METHODS

The immunohistochemical localisation of interleukin-1beta in biopsies of patients suffering from chronic active hepatitis was studied, using an affinity-purified rabbit polyclonal antibody.

RESULTS

The strongest interleukin-1beta immunostaining was observed in the above-described plasma cell population, identified by anti-immunoglobulin antibodies, and 3H-proline incorporation.

CONCLUSIONS

The ability of plasma cells to produce interleukin-1 during viral CALD suggests that in these pathologies plasma cells play a major role, mainly of paracrine nature. Interleukin-1, possibly together with other mediators, might in turn stimulate the production of collagen. Hepatocytes of the piecemeal necrosis area appear to be possible candidates for this synthesis, as they show a significant labelling after 3H-proline incorporation, which is absent from hepatocytes far from necrotic areas.

Primary biliary cirrhosis is associated with specific changes in liver IgG-bearing cell subpopulations

BACKGROUND/AIMS

The density of total IgG-bearing cells and the distribution of their subclasses were studied in the liver of patients with primary biliary cirrhosis.

METHODS

Immunohistochemistry and computerized image analysis were used to compare liver specimens from 18 patients with primary biliary cirrhosis and 28 with chronic hepatitis of different etiology.

RESULTS

The density of total IgG-bearing cells was similar in the two groups. However, in patients with primary biliary cirrhosis the proportion of IgG3-positive cells was significantly higher than in patients with chronic hepatitis (53 +/- 7% vs. 7.5 +/- 2.4%) (p < 10(-8)). Conversely, IgG1-positive cells were significantly less prevalent in patients with primary biliary cirrhosis than in chronic hepatitis patients (27 +/- 6.9% vs. 68 +/- 7.2%, p < 10(-8)). Stratification of patients with primary biliary cirrhosis according to histology did not show any difference in the distribution of IgG subclasses associated with the progression of disease.

CONCLUSION

These data suggest a pathogenetic role of local IgG3-bearing cells in primary biliary cirrhosis.