Figure 1c:

Graphs show ⁸⁹Zr-oxine labeling of various cell types did not require active cellular incorporation. (a) One million EL4 cells were incubated with the ⁸⁹Zr-oxine complex at 1:50 volume ratios in phosphate-buffered saline (PBS), serum-free medium, or complete medium at 37°C, room temperature (RT ), or 4°C for 15 minutes. Radioactivity associated with the cells was determined (n = 3, representative of two independent experiments, Y indicates P < .05 at two-way analysis of variance). (b) Labeling efficiency and (c) specific activity of DCs, naïve and activated CTLs, and NK, bone marrow, and EL4 cells (DC and naïve and activated CTLs: n = 4; NK, bone marrow, and EL4 cells: n = 3). Error bars indicate standard deviation.