Figure 4.

Granulocyte-macrophage colony-stimulating factor–activated monocytes (GMaM) infiltrate the intestine at higher numbers and persist longer. (A) GMaM and control monocytes were stained for cell surface expression of gut homing molecules and analyzed by flow cytometry. Expression is shown as representative dot plots gated on CD11b⁺ cells showing Ly6c expression (y axis) versus respective cell surface molecules (x axis). (B) GMaM and control monocytes were labeled with 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide and injected intravenously at day 13 of chronic dextran sulfate sodium–induced colitis. Monocyte infiltration in the intestine was visualized after 48 hours and 96 hours, and representative pictures are shown (n = 3). (C) After 96 hours, the intestine was removed and monocyte infiltration especially into Peyer’s patches, visualized by fluorescence reflectance imaging, was evaluated (arrow shows Peyer’s patches). (D) Mean fluorescence intensity (mean ± SEM) of Peyer’s patches is shown (n = 5–7). Statistical significance was determined by unpaired Student t-test. *P < .05.