Hybridization of a Myeloid Leukemia-Derived Human Cell Line (K562) With a Human Burkitt's Lymphoma Line (P3HR-1)2

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Abstract
The myeloid leukemia-derived Epstein-Barr virus (EBV)-negative human lymphoid cell line K562 was successfully hybridized with the EBV-carrying Burkitt's lymphoma line P3HR-1. Authenticity of the hybrid PUTKO-1 was established by chromosome and isoenzyme studies. A virtually complete hybrid PUTKO-1 carried the EBV genome derived from the lymphoma parent. It averaged 26 EBV DNA copies per cell and was 100% positive for Epstein-Barr virus-associated nuclear antigen (EBNA). In most respects, the hybrid resembled the K562 parent: It had a high Fc receptor concentration, high sensitivity to natural killer cells, absence of EBV C3 receptors, and deficiency of membraneassociated β2-microglobulin (β2M) and HLA, in parallel with intracellular synthesis and secretion of β2M to the medium. Unlike the P3HR-1 parent, the hybrid was completely nonpermissive for antigens of the EBV cycle, early antigen, and viral capsid antigen. None of the 3 inducing agents, 5-iodo-2′-deoxyuridine, 12-O-tetradecanoyl-phorbol 13-acetate, or sodium butyrate, caused any viral antigen synthesis in PUTKO-1 in contrast to the good inducibility of the parental P3HR-1 subline. Thus the myeloid parent restricted expression of EBV antigens except EBNA. This exception further supports the concept that EBNA is an autonomous function of the viral genome, independent of host cell control that regulates expression of antigens related to the viral cycle. On the contrary, extinction of viral antigens in this hybrid between 2 cell lineages supports our previous concept that the ability to produce viral antigens is similar to a differentiated B-cell property.