Augmentation of murine hematopoiesis by interleukin 2-activated irradiated T cells.

We have examined the role of T cells activated with interleukin-2 (IL-2) in vitro and subsequently irradiated (2500 rads), in stimulating murine hematopoiesis in a syngeneic system. Our data suggest that activated, irradiated T (AIT) cells significantly increased the progenitor cell activity of T cell-depleted bone marrow (BM) both in vitro and in vivo as compared with controls (P 0.05). Optimal stimulation of BM progenitor cell activity was seen when T cells were activated for 4 days and used in a BM to T cell ratio of 1 :2 or 1 :5. The effect of these activated cells was related to the release of factors with ability to enhance hematopoiesis. These observations may have implications in enhancing the engraftment of T cell-depleted BM in allogeneic transplantation.