Ricin-resistant human T-cell hybridomas producing interferon gamma

Ricin-resistant variants of the SH9 T-cell line were selected after growth of this line in medium containing toxic amounts of ricin, a lectin derived from Ricinus communis. The ricin-resistant SH9 lines, SH9.R0 and SH9.R1, were demonstrated to be deficient in cell surface ricin-binding sites, but otherwise had the cellular phenotype of SH9 cells. Ricin-resistant T-cell hybridomas were prepared by fusion of SH9.R0 and SH9.R1 with activated T-lymphocytes. The presence of ricin in the selection medium rapidly killed unfused T-lymphocytes and prevented cell transformation by human T-cell leukaemia virus type 1 (HTLV-1) which is shed by the SH9.R0 and SH9.R1 cells. This ensured that the cells growing out were indeed hybridomas. Ricin-resistant T-cell hybridomas were characterised and also shown to lack cell surface receptors for ricin. Analysis of T-cell surface markers indicated that the T-cell hybridomas could be the result of fusions between SH9.R1 cells and T-helper lymphocytes or T-suppressor lymphocytes. All of the T-cell hybridomas prepared in this study spontaneously produced interferon gamma (IFN gamma).