Establishment and characterization of a Kaposi's sarcoma-associated herpesvirus- and Epstein-Barr virus-negative malignant lymphoma cell line (OHK) with primary effusion lymphoma immunophenotype

A novel cell line, designated OHK, was established from ascites of a 59-year-old Japanese woman with diffuse large B-cell lymphoma showing a peculiar serosal tropism. as seen in primary effusion lymphomas (PEL). OHK exhibited a large pleomorphic morphology with irregular nuclei and distinct nucleoli, and included immunoblastic and Reed-Sternberg-like giant cells. On ultrastructural examination, rich intermediate filaments, and well-developed Golgi apparati and rough endoplasmic reticulum, were seen. Immunophenotypically, OHK lacked T and B cell-associated antigens, and had CD10, CD30, CD33 and CD138 antigens. Although ORK cells did not express immunoglobulin (Ig) protein, Southern blot analysis demonstrated clonal rearrangements of Ig heavy and light chain genes. These observations suggest that OHK cells are derived from preterminally differentiated B cells, and that they have features of PEL. Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus were not detected. OHK displayed hyperploid karyotypes with multiple structural abnormalities, and produced some cytokines such as macrophage-colony-stimulating factor (M-CSF), granulocyte-CSF, interleukin 6 and transforming growth factor beta1. In particular, vascular endothelial growth factor (VEGF). whose stimulation of vascular permeability is thought to be critical to the pathogenesis of PEL, was also produced in large quantities. These results indicate that ORK may be a useful tool for the investigation of PEL.