Posttransplant dermal DC and macrophage chimerism. (A) Dual immunofluorescence (left) and FISH (right) of migrated dermal cells from a female recipient 40 d after transplantation. Donor-derived HLA-DR⁺CD14⁻ DC and HLA-DR⁺CD14⁺ DC can be seen together with a mixture of CD3⁺ lymphocytes and a single recipient HLA-DR^+CD14⁺FXIIIa⁺ macrophage. A small number of FXIIIa⁺ macrophages were seen in migratory preparations and, like the one shown, were often recipient in origin but more lightly granulated than the cells released from digested preparations. Bar, 20 µm. Dashed line indicates stitching of high-power fields. The representative example was taken from the cohort of 52 patients. (B) Dual immunofluorescence (left) and FISH (right) of remnant digested dermal cells from a male recipient 40 d after transplantation. Two donor-derived HLA-DR⁺CD14⁻ dermal DC can be seen together with three recipient HLA-DR⁺CD14⁺FXIIIa⁺ macrophages and number of unlabeled stromal cells. Autofluorescent melanin is visible on the FISH image of the FXIIIa⁺ cells, confirming their identity as macrophages. Bar, 20 µm. Dashed line indicates stitching of high-power fields. The representative example was taken from the cohort of 52 patients. (C) Engraftment kinetics of dermal DC and macrophages compared with blood myeloid cells, derived from a cohort of 52 patients biopsied at 40, 100, and 365 d after transplant. Error bars show SD. *, P <0.001 compared with any other population (Mann-Whitney U test); **, P = 0.02 comparing CD14⁺ DC with CD14⁻ DC (Wilcoxon rank sum test). (D) Engraftment kinetics of each cutaneous APC as a function of intensity of conditioning and prior GVHD. GVHD has a significant effect on LC engraftment both at 40 and 100 d but does not influence macrophage engraftment. Error bars show SD. *, P < 0.05 (Mann-Whitney U test).