RESUMO
BACKGROUND: Cell lines can be established when the cells are clonally selected and propagated continuously in vitro culture system. Recently we established a B cell line (KEB1) from the bone marrow cells of the patient infected with Epstein-Barr virus (EBV). METHODS: The patient's initial platelet count was 1,000/microliter and peripheral blood smear showed atypical lymphocytes accounting 20% of the differentials of WBC. Antibodies to EBV and PCR for EBV were positive but heterophil antibody was negative. Mononuclear cells were obtained by Ficoll-paque separation and suspended in RPMI media with 10% FCS. After incubation in 37degrees C, 5% CO2 incubator, cells grew continuously and finally immortalized to B cell line. RESULTS: Cells showed abundant, clear basophilic cytoplasms and a few vacuoles. Cells had granular reaction in PAS stain and were positive to B cell antibodies. Immunohistochemical stain showed positive expression for EBV antibody. Electron microscopic finding of cultured cells showed several viral particles, and immunoelectron microscopic finding showed electron dense expression. Immunophenotyping of cultured cells was positive for B lymphoid lineage, and karyotypings had hypotetraploidy. Cells expressed MAGE and SSX gene. Cytotoxicity showed relative resistance to mistletoe and several chemotherapeutic agents compared to leukemic cell line. CONCLUSION: KEB1 cell line was established from the bone marrow cells of the patient with infectious mononucleosis. The characteristics of the cell lines including morphology, immunophenotype, karyotype, gene analysis (MAGE, SSX) and chemosensitivity were analyzed. There should be further studies of these cell lines including gene analysis, telomerase activity and cytokine production. This cell line might be helpful to establish another normal lymphocyte cell line and to predict the toxicity of chemotherapy.