Phagocytic Activity Measured by Dextran Uptake. (A-B) Immunofluorescence of exogenous rhodamine-labeled dextran (red) uptake with ImageJ markings (crosshairs) of counted dextran maximas. 20 μg/ml chloroquine-treated cells at 24 hours (B) showed striking decrease in fluorescent dextran uptake when compared to control (A). (C) Quantization of dextran uptake between control and chloroquine-treated ARPE-19. There is a significant (p < 0.05) decrease in relative dextran uptake in individual sampled ARPE-19 cells between control and chloroquine-treated cells. Quantitation was performed by using ImageJ, isolating cells of relative same size (~20-25 microns), and then calculating florescent maximas (tolerance = 20, based on control). Maximas were averaged and standard t-test was performed (n = 10).