HCV and lymphoproliferative diseases

Genomic and replicative forms of HCV-RNA in B lymphocytes were detected by RT-PCR, and HCV genotyping was performed using universal and type-specific primers for the core region. Immunoglobulin gene rearrangement was detected by RT-PCR.

The presence of genomic and replicative forms of HCV-RNA in the 5'NC region was investigated on total RNA extracted from subpopulations of PBMC. The frequency of HCV-RNA was higher in the B lymphocytes than in other PBMC. In two patients a larger sized band was present in the B lymphocytes and PMN; this band could represent either another form of HCV-RNA or a cross-reaction between cellular RNA and HCV primers. HCV-RNA detected using primers for the core region was negative in the patients examined. Immunoglobulin monoclonal gene rearrangement was present on the cDNA in all of the HCV and type II cryoglobulinemia positive samples except two; in contrast, it was absent in the HCV positive and cryoglobulinemia negative samples. The analysis of immunoglobulin monoclonal gene rearrangement on DNA showed the presence of new positive samples among the HCV positive, type II cryoglobulinemia negative patients, who had been negative when PCR was performed on cDNA. Denaturing sequencing gel showed clearer results than agarose gel.

The early detection of immunoglobulin monoclonal gene rearrangement and expression is very important because it could provide evidence of the possible lymphoproliferative evolution of HCV infection. In addition, these investigations together with PCR product sequencing could show us the steps in the clonal selection of B lymphocytes towards malignant transformation, in which HCV plays a direct and/or indirect role.