Flow cytometric analysis of CD18⁺ myeloid cells in the peripheral blood prior to and following matched littermate transplantation. Peripheral blood leukocytes were isolated, stained with anti-CD18 FITC antibody, and examined by flow cytometry. Myeloid cell populations were gated on forward scatter and side scatter profiles and are identified by side scatter (y-axis) and FL1 fluorescence intensity (x-axis) in the dot plots. The times indicate before transplantation and after transplantation times of 1 month (4 weeks), 6 months, 9 months, and 12 months, respectively. CD18⁺ myeloid cell percentages are indicated within the box. The few cells appearing in the boxes of dogs D102 and D114 at the pretransplantation time points are not statistically different from cells stained with isotype controls. Side scatter was adjusted in some cases to clarify myeloid from lymphoid populations. For dog D114, pretransplantation FL1 intensity was changed from linear scale to log scale.