Figure 3.

Activated lung macrophages are responsible for the uptake of folate-PEG-Cy5. At 48 hours after intratracheal LPS (3 μg/g body weight), total lung macrophages were isolated from lung lysates by adherence to tissue culture dishes for 2 hours and incubated with Cy5-PEG-folate (50 nM) for 30 minutes at 37°C. (A) Flow cytometry indicating that over 90% of adherent cells were macrophages (CD45⁺/CD68⁺). Representative microphotographs demonstrating colocalization of FRβ expression and folate uptake (yellow) in lung macrophages. (B) Representative ex vivo images showing folate-PEG-Cy-5–derived lung fluorescence and (C) photon counts from lungs of LPS-treated mice given control (PBS) or clodronate (Clod) liposomes (mean ± SEM; n = 3–6 per group; *P < 0.05).