Magnetophoretic mobility histograms of human peripheral blood leukocytes, (A, B), MCF-7 human breast cancer cells, (C, D), and KG1a human cell line, (E, F). For panels A, C, and E, the cells were incubated with unconjugated MACS magnetic nanoparticle following a standard company protocol (10 μl of MACS reagent in a total suspension of 100 μl containing 1 × 107 cells) and in panels B, D, and F, a high concentration of unconjugated MACS reagent (100 μl of MACS reagent in a total suspension of 100 μl containing 1 × 106 cells) was used. To determine if the nonspecifically bound MACS reagents could be washed off, the mobility after one, two and three washings was determined.