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. Pre-incubation 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 less than 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 less than 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 less than 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.