Endocytic activity of PAM3- and M-CSF–generated monocytes. Purified monocytes were stimulated in vitro for 5 days and then incubated with 50 µg/mL of labeled dextran particles for 45 minutes at 4°C or 37°C. Uptake represents the difference in fluorescence intensity at 4°C vs 37°C for each stimulant (mean ± standard deviation of 5-6 independently studied donors per group). **P < .01, ***P < .001 vs unstimulated cultures; +P < .05 PAM3 vs M-CSF cultures.