FDCs rapidly capture a soluble Ag injected subcutaneously. (A) WT mice were injected with 10 μL (50 μg) of Alexa 488–conjugated WGA (green) in the ears. Thirty minutes later, ear-draining LNs were collected; sectioned; stained for B220 (white), FDC-M2 (red), and collagen IV (blue) expression; and analyzed by confocal microscopy. Insets show the enlargement of a region that contains FDCs and conduits. (B) WT mice were injected with 10 μL (20 μg) of OVA or HEL in the ears. Ear-draining LNs were harvested 30 minutes later, sectioned, stained for HEL (green) and FDC-M2 (red) expression, and analyzed by confocal microscopy. (C) WT mice were injected with 10 μL (50 μg) of Alexa 488–conjugated WGA (green) in the ears. One, 5, 10, and 20 minutes later, ear-draining LNs were collected, sectioned, and stained for FDC-M2 (blue) and collagen IV (red) expression to examine the WGA diffusion over time when analyzed by confocal microscopy. Data were acquired with a Leica Sp5 microcope (×20 and ×63 objectives) and are representative of 3 different experiments. Scale bar: 100 μm.