Depletion of macrophages markedly reduces lymphatic flow and mobilization of inflammatory cells from the inflammation site of ear skin to DLNs. CDL (25 mg/kg, CD) was given intravenously to deplete macrophages at 1 day before and after the intradermal injection of PBS (PBS + CDL), LPS (LPS + CDL), or LTA (LTA + CDL). As a control, CL (25 mg/kg, C; PBS + CL, LPS + CL, LTA + CL) or PBS (P) only was given in the same manner. (A-C) Three days later, 3 μL FITC-conjugated dextran was intradermally injected into the same sites. Fluorescence intensities were determined in DLNs at 30 minutes after the injection (A), quantified, and presented as relative radiance (photons/sec per cm²/steradian; panel C). Panel A right bar: the color scale indicates fluorescence intensity. Upper red color indicates maximum fluorescence intensity, whereas lower blue color indicates minimum fluorescence intensity. (B) In parallel, at 30 minutes after the FITC-dextran injection, the DLNs are imaged by a fluorescence stereomicroscope. (D-F) At day 3 after intradermal injection of LPS or LTA, GFP⁺ inflammatory cells (∼ 10⁶ cells) were injected intradermally into the inflamed skin. Twelve hours later, the DLNs were sampled and sectioned for histologic analysis or digested for flow cytometry. (D,E) Pericapsular and paracortical regions of DLN sections were coimmunostained for LYVE-1 and DAPI, and merged. Scale bars represent 50 μm. GFP⁺ inflammatory cells in the section are quantified and presented as AU. (F) Flow cytometric analysis of GFP⁺ inflammatory cells in the DLNs after collagenase digestion is shown. All bars and numbers represent mean ± SD from 4 to 5 mice. *P < .05 versus P; ^#P < .05 versus LPS + CL or LTA + CL.