Functional properties of dermal myeloid cells. (A) Differential migration of dermal myeloid cells. 1-cm square dermal sheets were freshly digested with collagenase or incubated in RPMI 10% FCS for 72 h in low adhesive culture plates, after which migrant cells were collected and the remnant dermis was digested to release nonmigrating cells. CD45⁺HLA-DR⁺ gated cells were analyzed by SSC and AF and further separated into CD14^+/− fractions as described in Fig. 1. Populations a–e were sorted by flow cytometry for morphological analysis as shown. CCR7 expression was determined on freshly isolated populations. The experiment was repeated 12 times with similar findings. Bar, 20 µm. (B) Phagocytosis of FITC dextran by dermal myeloid cells. 5 × 10⁵ collagenase-digested dermal cells were incubated with 1 mg/ml of FITC-coated dextran particles at 37 or 4°C for 1 h in RPMI containing 10% FCS. Cells were harvested and washed before immunostaining. Fluorescence histograms show a representative example. For the bar charts, all three are independent experiments. ΔMFI, change in geometric mean fluorescence compared with no dextran control. (C) Adherence of dermal myeloid cells. 5 × 10⁵ collagenase-digested cell suspensions were cultured overnight in RPMI containing 10% FCS. Nonadherent cells and washes were collected and pooled. Adherent cells were removed by trypsinization. Flow cytometric analysis was performed using SSC, AF, CD14, and CD1a according to Fig. 1. A representative example is shown with the cumulative results of five independent experiments. Bars represent the means.