Teleocidin-induced phenotypic changes in thymic ALL cell line, HPB-ALL

An indole alkaloid, teleocidin, induced phenotypic differentiation in the thymic ALL cell line HPB-ALL. Within 30 min of seeding in the presence of teleocidin, the cells formed a smooth round shape. Upon 5-day exposure to teleocidin, most of the cells became smaller and reminiscent of large or atypical lymphocytes. A thymic antigen stained with monoclonal antibody OKT6 was remarkably reduced while Leu2a-positive cells were increased in the treated cells. Upon teleocidin-induced phenotypic differentiation, the growth rate of cells was inhibited, their ability to incorporate DNA via [3H]-labelled precursors was reduced, their ability to bind sRBC rosettes was increased. These changes were paralleled to that induced by 12-o-tetradecanoyl-phorbol-13-acetate.