FIG. 2.

Internalization of ¹²⁵I-labeled 7G7/B6 and modulation of CD25. (A) Internalization of ¹²⁵I-7G7/B6 by SUDHL-1 and kit225IG3 cells. Cells were incubated with ¹²⁵I-7G7/B6 for 1 hour at 4°C for surface labeling. After washing, the cells were incubated at 37°C for 0, 1, 3, 6, and 24 hours. The relative percentages of radioactivity associated with cells and in the supernatant, which was further differentiated by methanol precipitation as free and precipitable, are depicted as a function of time. The data represent the mean of triplicates. (B) Flow cytometric analysis showed that the binding of daclizumab to SUDHL-1 and kit225IG3 cells was not affected meaningfully by incubation of the cells with unmodified 7G7/B6 at a concentration of 20 μg/mL for 24 hours.