Figure 3: p210-cBSA is preferentially taken up by antigen presenting cells in vitro. Uptake of FITC-labeled p210-cBSA by splenocytes was studied by confocal microscopy (A) and flow cytometry (B) after in vitro incubation with 50 μg/ml FITC-p210- cBSA at 37°C. Representative immunofluorescence microscopy picture visualizing cell nucleus in red and FITC-p210-cBSA positive splenocytes in green. Flow cytometry results showing mean fluorescence intensity (MFI) of FITC-p210-cBSA in cells gated as CD11c positive, MHCII positive or MHCII negative. Increasing concentrations unlabeled p210-cBSA was added to in vitro cultures of splenocytes and 25 μg/ml of FITC-labeled p210-cBSA. Uptake of FITC-p210-cBSA was determined by flow cytometry and presented as mean fluorescent intensity in CD11c+ and MHCII+ cells (C). Uptake of FITC-labeled p210-cBSA or FITC-labeled p210 was studied in CD11c+ cells after in vitro incubation with the respective antigen (D). Uptake was determined as MFI of the CD11c+ cells.