Enhancement of normal human hematopoiesis in transgenic NOD/SCID-β2m^-/- mice producing human IL-3, GM-CSF, and SF. Each panel shows the time course of changes in the number of different types of human cells present in the BM of NOD/SCID-β2m^-/--3/GM/SF (solid lines) and NOD/SCID-β2m^-/- mice (dotted lines) from 3 to 20 weeks after being injected with 4 × 10⁵ normal human lin^- BM cells. Values are the mean ± SEM of results obtained from individually assessed mice (6 mice/group) and were calculated by multiplying the average proportion of cells with the phenotype shown within aspirated samples by the total number of cells present in the BM of similar mice determined from a large data set from other experiments.