Donor-derived cells are present in the PB from recipients of either wild-type orSHIP^-/-BM cells. Aliquots of PB were collected from Pep3b recipients that received transplants 16 weeks previously of 5 × 10⁵ BM cells from either SHIP^+/+ (wild type; left panels) or SHIP^-/- (right panels) donors. FACS staining and analysis were carried out as indicated in “Materials and methods.” Representative FACS profiles indicating the frequency of donor-derived (Ly5.2⁺; right quadrants) and endogenous (Ly5.2^-; left quadrants) B-lymphoid (B220⁺) and myeloid (Mac-1/Gr-1⁺) cells are shown.