Kinetics of cellular oncogene expression in mouse lymphocytes. I. Expression of c-myc and c-ras-Ha in T lymphocytes induced by various mitogens.

Murine splenic T lymphocytes display maximal cellular myc gene (c-myc) expression already 3 h after concanavalin A stimulation and subsequent down-regulation before the onset of DNA synthesis. Stimulation by leucoagglutinin in the presence or absence of interleukin 2 leads to only low initial levels of c-myc-specific RNA which, however, increase later on. A similar pattern of c-myc expression is shown by the Lyt-2+ T cell subpopulation stimulated with either concanavalin A or leucoagglutinin in the presence of interleukin 2. Although [3H]thymidine incorporation was identical, the leucoagglutinin-stimulated Lyt-2+ T cells were void of any demonstrable c-myc-specific RNA at 3 h post-stimulation. Thus, the kinetics of c-myc expression in mouse T lymphocytes are not at all uniform, but depend on the mitogen and the subpopulation. In contrast, levels of c-ras-Ha-specific RNA were always low at early times, always increased towards the onset of DNA synthesis and down-regulation was not observed.