Establishment of four new mesothelioma cell lines: characterization by ultrastructural and immunophenotypic analysis

The aim of this study was to assess the biological characteristics of four new malignant mesothelioma (MM) cell lines. Since simian virus (SV)40 seque nces have been recently detected in MM, SV40 large T antigen (Tag) expressi on was also analysed, MM cell lines were characterized by morphological, ultrastructural and cyto genetic analysis. Expression of Tag and of relevant MM markers was studied by immunocytochemistry, surface antigens by indirect immunofluorescence and immunomodulating cytokines by enzyme-linked immunosorbent assay (ELISA). The four MM cell lines, established from pleural effusions, showed a slow p roliferation rate and pleomorphic changes during culture. Cell lines expres sed vimentin, cytokeratins 8 and 18, and the mesothelial antigen recognized by HBME-1 monoclonal antibody, but not carcinoembryonic antigen. Surface h uman leukocyte antigen (HLA)-class I and intercellular adhesion molecule (I CAM)-1 molecules were present on all the cell lines. While HLA class II and CD86 were constitutively undetectable, HLA-class II was present after inte rferon (IFN)-gamma stimulation, All cell lines displayed abnormal karyotype s with chromosome 6 abnormalities, Transforming growth factor (TGF)-beta(2) and interleukin (IL)-6 were constitutively secreted, while tumour necrosis factor (TNF)-alpha was secreted only in response to lipopolysaccharide, In tranuclear Tag was expressed in two cell lines. The persistence of large T antigen with human leukocyte antigen class I and intercellular adhesion molecule-1 positivity may point to large T antigen as a target for cytotoxic T-lymphocyte-based immunotherapy in some malignan t mesothelioma patients.