Control of human T-colony formation by interleukin-2.

T-colony formation can be induced in PHA-stimulated peripheral blood mononuclear cells (PBM) from man, but not in PHA-stimulated purified T cells, the latter requiring the presence of factors produced by PHA-stimulated PBM and termed T-colony promoting activity (TCPA). In this paper, we demonstrate that interleukin-2 (IL-2), the growth hormone of T lymphocytes, controls T-colony formation. We show that: IL-2 activity and TCPA produced by PHA-activated PBM are co-purified by gel filtration and chromatography on blue agarose, a procedure which yields a 850-fold IL-2 purification; recombinant IL-2, produced by genetically manipulated Escherichia coli, can induce T-colony formation in PHA-stimulated purified T cells; Monoclonal antibody against the IL-2 receptor (anti-Tac antibody) completely inhibits the T-colony formation in PHA-stimulated PBM when directly added to the culture system.