Expression of c-myc in Stimulated T Lymphocytes of the Helper/Inducer Phenotype Producing Lymphokine(s) Supporting Multilineage Colony Formation

Abstract

Phytohemagglutinin (PHA) renders human peripheral T lymphocytes competent to replicate their DNA and divide. The stimulation of peripheral T cells of the T4 phenotype by PHA, which appears to be a transcription-dependent event, leads to the production and release of lymphokines supporting proliferation and differentiation of human pluripotent stem cells (CFU-GEMMT). Supernatants of PHA-stimulated lymphocytes of the suppressor/cytotoxic phenotype (T8) failed to demonstrate reasonable activity to support the growth of CFU-GEMMT. Stimulation of T lymphocytes of the T4 but not of the T8 phenotype leads to an increased intracellular level of c-myc mRNA. This would be consistent with the c-myc gene product functioning as an intracellular mediator of the growth and lymphokine production response to PHA. Although the function of the c-myc gene product is not yet clear, it seems likely that it is involved in the control of cell proliferation. Such a contribution to control of cell proliferation by c-myc would probably be mediated by a family of genes inducing lymphokine production to stimulate proliferation of human pluripotent stem cells.