Abstract

Human lymphoblastoid B-cell lines immortalized by Epstein-Barr virus (EBV) were established from peripheral blood of patients with acute myeloblastic and chronic lymphocytic leukemia and chronic fatigue syndrome. The sera of patients with acute myeloblastic and chronic lymphocytic leukemia did not show antibodies to Epstein-Barr viral capsid antigen (VCA), but serum of a patient with chronic fatigue syndrome disclosed antibodies to VCA (IgG, IgM), and EBNA was demonstrated in peripheral blood mononuclear cells by polymerase chain reaction. The established cell lines were mature B-cell phenotypes with polyclonal proliferation in early passage and no evidence for commitment to other lineages. The immortalized cells by EBV were designated as CSUP-1 and CSUP-2 (from acute myeloblastic leukemia, FAB classification M2 and M1), CSUP-3 (from chronic lymphocytic leukemia) and CSUP-4 (from a patient with chronic fatigue syndrome). The CSUP-1, 2, 3, and 4 grew in suspension forming clumps with a doubling time of 38 to 49 hours. Colony formation was not recognized in plate. By light and electron microscopic examination, the immortalized cells showed features of lymphoblastoid to plasmacytoid lymphocytes, and multinucleated giant cells. The lymphoblastoid cells showed scanty cytoplasm with poorly developed organelles. Immunophenotypic analyses of CUSP-1, 2, 3, and 4 with monoclonal antibodies by flow cytometry showed B-cell phenotype with polyclonal proliferation in early passage. Epstein-Barr virus nuclear antigen was confirmed in the extracted DNAs from immortalized cells by polymerase chain reaction. DNA analysis showed a normodiploid stemline with a DNA index of 1.12. The established cells were strongly reactive for CD10, CD30 (Ki-1) in early passage, and bcl-2 and c-myc onco-protein in early and late passage. Karyotypic analysis of CSUP-1, 2, 3 and 4 showed 46, XY or 46, XX. No tumorigenesis in heterotransplanted SCID mouse was recognized. This immortalized cells by EBV should be a valuable cell lines to study the pathogenesis of EBV-related malignant lymphoma.

• Keywords: Lymphoblastoid-B cell line;Epstein-Barr virus;Polyclonal and monoclonal proliferation;PCR;Flow cytometry