Transforming growth factor-beta 1 and T-lymphocytes modulate the growth of human peripheral blood progenitor cells

This study examined the effects of transforming growth factor-beta 1 (TGF-beta 1) and autologous T-lymphocytes on the growth of day-14 granulocyte-monocyte progenitor cells (CFU-GM). Mononuclear cells from human peripheral blood were depleted of accessory cells, yielding "B/null" or "null" cell populations enriched 17-fold and 94-fold, respectively, for CFU-GM. Addition of TGF-beta 1 to B/null or null cells caused a dose-dependent decline in CFU-GM cloning efficiency. The addition of unstimulated autologous T cells to B/null or null cells enhanced CFU-GM growth both in the absence and presence of TGF-beta 1. T cells enhanced growth of all CFU-GM colony types to equal extents, whereas TGF-beta 1 inhibition preferentially reduced the proportion of macrophage colonies. TGF-beta 1 concentrations that blocked T-cell proliferation did not interfere with the capacity of T cells to enhance CFU-GM growth. The data suggest that noncycling T cells can reduce the inhibitory effects of TGF-beta 1, most likely through production of one or more stimulatory cytokines.