Microplate method for retrovirus-induced transformation of normal human T-cells

An adult T-cell leukemia virus (ATLV) producer cell line (TL-Su) derived from a healthy ATLV-carrier, was used for virus-induced transformation of normal human T-cells. The transformation was carried out on microplates by co-cultivation of a limiting number of normal peripheral blood leukocytes (PBL) as transformed target cells and 2 X 10(4)/well of TL-Su cells irradiated lethally. The frequency of establishment of transformed cell lines correlated with the dose of PBL. The transforming target cell number was estimated to be approximately one per 500 PBL by the microplate method using TL-Su effector cells. When 1 X 10(3) PBL per well were plated, more than 90% of wells showed immortalizing transformation of PBL. Twenty transformed cell lines obtained from microplates with 500 PBL per well were shown to be of T-cell lineage. Ten of them were defined as belonging to the helper/inducer T-cell subset with Leu 3a antigen, and 4 were demonstrated to be of the cytotoxic/suppressor T-cell subset with Leu 2a antigen. The transformed cells always expressed Tac and OKT9 antigens (considered to be IL2 and transferrin receptors respectively). ATLV antigens were also expressed in all these cell lines tested, but their molecular species detected by radioimmunoprecipitation varied regardless of PBL donors and T-cell subsets. We propose this microplate transformation method as an advantageous system for obtaining abundant T-cell lines and for screening their immunological functions.