CXB-12 cell numbers and repopulating abilities per cell.

The observed donor cell percentages after 6 months for the 37 recipients in the competitive dilution assay described in “Materials and methods” are ranked from low to high and shown as OBS (●). We hypothesized 3 levels of repopulating potential—“F” for each CXB-12 donor HSC relative to F = 1 for each CByB6F1 competitor HSC; F = 1 (♦), F = 2 (⋄), and F = 1.4 (○)—and generated 3 sets of predictions based on combined Poisson probabilities as described in “Materials and methods.” The predictions from models F = 1 and F = 2 were significantly different from actual observations; thus, models F = 1 and F = 2 were rejected. Predictions from model F = 1.4 were not significantly different from actual observations. Thus, F = 1.4 best represents the repopulating ability of a CXB-12 HSC relative to that of a CByB6F1 HSC.