FasL expression in lin− BMs did not inhibit generation of CFCs or syngeneic in vivo engraftment, assessed early after BMT.
(A) B6.SJL lin− BMs were transduced with either the FasL(-GFP fusion) or control GFP vector as described in “Materials and methods,” then 3 × 103 cells were plated in CFC assay medium as described in “Materials and methods.” The results are the averages (and SEM) of 4 separate experiments. (B) CFCs were assayed from untransduced B6.SJL lin− BMs that were exposed to sFasL in vitro, at the concentrations indicated, for 24 hours prior to plating in methylcellulose. Colonies were counted 7 days later; shown are the averages of 2 separate experiments. (C) BALB/c lin− BMs were transduced with either the GFP control or FasL vector, then 105 cells were transplanted into 850-cGy irradiated syngeneic mice (5 mice/group). Shown is the histogram of GFP expression in the starting population of transduced lin− BMs. (D) At 3 weeks after transplantation of the cells shown in panel C, mice were tail bled to determine the percentage of circulating transduced cells. Whole blood was collected by tail bleeds and red cells removed by hypotonic lysis, then analyzed by FACS for GFP expression. The graph shows the percent GFP+ blood cells after transplantation (each point represents one mouse).
