Stimulator T-Cells and the Regulation of Growth Factors Produced in the Murine Mixed Leukocyte Reaction

Abstract

Previous work had implicated T cells within the stimulating population as having a significant role in the MLR. We now report that depletion of T cells from the stimulators caused a reduction in proliferative response in mixed leukocyte reaction (MLR) by 50% or more. This response could be restored by adding T-enriched cells from the stimulators but not from the responders. During MLR, the T-cells in the stimulating population demonstrated changes characteristic of early activation, namely, increase in RNA synthesis. Stimulator T-cells have been shown to regulate the interleukin 2 (IL 2) production in mixed leukocyte culture (MLC). Depletion of T cells from the stimulators reduced the level of IL 2 in the culture. Addition of IL 2 to the cultures containing T-depleted stimulators reconstituted the proliferative response. Our data suggest that there may be alternative ways of producing It 2-like growth factors. Depletion of T cells from the stimulators allows the detection of a growth factor which differs from IL 2 in its mode of production. We conclude that optimal proliferation in the MLR requires that the stimulating population contain T cells which regulate the growth factors in the culture.