rGM-CSF and rGM-CSF/rIL-4 increased antigen capture by splenic DCs.

DC-enriched splenocytes from control and cytokine-treated mice were incubated with 1 mg/mL FITC-dextran or Lucifer yellow for 1 hour at 37°C, stained with CD11c and CD11b to identify DC subsets, and analyzed by FACS for receptor-mediated endocytosis of FITC-dextran (A) or pinocytosis of Lucifer yellow (B), as determined by mean fluorescence intensity (MFI). Uptake at 37°C is shown in the upper bars, and uptake of cells incubated at 4°C is demonstrated by the lower bars. Both DC subsets responded to in vivo GM and GM/IL-4 with significant increases in endocytosis; the greatest response was observed in GM/IL-4–treated mice. In contrast, only DCs from GM/IL-4–treated mice demonstrated increased pinocytosis. Data are from a representative experiment (n = 5). *P ≤ 0.05 compared with control; †P ≤ .05 compared with GM. □ indicates control; , GM; ■, GM/IL-4.