Establishment and characterization of a human EBV-negative B cell line (MN 60)

A permanent cell line, MN 60, was established from the peripheral blood of a patient with an acute lymphoblastic leukemia (ALL) classified morphologically as being of the L3 type. Cell growth started rapidly in vitro and no feeder cells were needed. Cells of the MN-60 line were identical to the original leukemic cells with respect to surface immunoglobulin (Ig) expression and karyotype, including the presence of four marker chromosomes [1q+, 6q-, t(8;14)]. Continuous proliferation was maintained in stationary suspension culture with a doubling time of 25 h. The cells were tumorigenic in athymic nude mice and had the capacity to form colonies in semi-solid medium in vitro. Monoclonal surface Ig (mu lambda) was demonstrated whereas no cytoplasmic immunoglobulin could be demonstrated. The MN-60 cells were Epstein-Barr virus (EBV) negative as evidenced by EBNA tests and by nucleic acid hybridization studies. The cells expressed HLA-A-C, HLA-DR. beta 2-Microglobulin and cALL, but not Fc gamma. C3, sheep and mouse red blood cell receptors. No reactivity was found with anti-glycophorin A or the anti-BL 38.13 monoclonal antibody. Cell growth was retarded in the G0/G1 phase of the cell cycle after incubation with leukocyte interferon, hydrocortisone, phorbol myristate acetate and dimethyl sulphoxide.