Analysis of the transformation of human lymphocytes by Epstein-Barr virus. II. Abortive response of leukemic cells to the transforming virus

Abstract

Leukemic lymphocytes with B-cell markers were obtained from the peripheral blood of 4 patients with chronic lymphocytic leukemia (CLL) or acute lymphocytic leukemia (ALL); a significant number of T cells was not involved. The lymphocytes were inoculated with the transforming B95-8 Epstein-Barr virus (EBV). Synthesis of EBV-determined nuclear antigen (EBNA) occurred in three CLL preparations: 15.1--25.4% of cells expressed maximum EBNA 24--48 h after viral exposure. A characteristic immunofluorescence pattern similar to a coarsely clumped chromatin structure was observed. In contrast to EBV infection of normal lymphocytes, EBNA synthesis in CLL cells (morphologically similar to normal lymphocytes) was not followed by either blastogenesis or DNA synthesis. EBNA-positive cells, which usually degenerate within 1--2 weeks, could be maintained for more than 30 days on feeder human embryo fibroblasts pretreated with mitomycin C. DNA synthesis and mitosis occurred, but unlimited cell growth did not. 41.9% of ALL cells were EBNA-positive at 36 h prior to DNA synthesis, and they subsequently grew rapidly for up to 9 days. The cell proliferation, however, was temporary, and death resulted in about 2 weeks. No significant synthesis of EBV-related early antigens and viral capsid antigen was noted in any of the infected cultures throughout the incubation period. These results indicate that certain intracellular restrictions may have exceeded the potent transforming capacity of EBV in these target leukemic cells.