The use of recombinant cytokines for enhancing immunohematopoietic reconstitution following bone marrow transplantation. I. Effects of in vitro culturing with IL-3 and GM-CSF on human and mouse bone marrow cells purged with mafosfamide (ASTA-Z)

Enhanced colony formation (CFU-GM) in vitro was observed in murine and human bone marrow (BM) cells following pre-incubation for 2-3 days with recombinant murine GM-CSF or natural purified murine IL-3, and recombinant human GM-CSF or IL-3, respectively. Preincubation in the presence of both GM-CSF and IL-3 produced additive stimulatory effects. BM cells previously treated in vitro with mafosfamide (ASTA-Z) under conditions identical to those used in the purging of autologous BM grafts, also demonstrated an enhanced cumulative response to combinations of GM-CSF and IL-3, with up to 100-fold increase in CFU-GM as compared with controls (p < 0.001). In mice, the number of CFU-S was also significantly increased (2-20 times) following incubation of unpurged and purged BM cells in murine IL-3 and/or GM-CSF. Interestingly, the frequency of both CFU-GM and CFU-S in BM cells first purged with ASTA-Z and then cultured with both cytokines was significantly higher (p < 0.01) than that in fresh, intact BM cells. In addition, mice transplanted with unpurged or purged, cytokine cultured syngeneic BM cells exhibited a significantly (p < 0.01) earlier reconstitution of peripheral white blood cells and of BM CFU-GM, and a significantly enhanced anti-sheep red blood cell plaque-forming cell response. Overall, the data suggest that it might be possible to enhance immunohematopoietic reconstitution in recipients of unmanipulated, as well as ASTA-Z purged autologous BM following short-term culture of BM cells with recombinant colony stimulating factors prior to bone marrow transplantation.