Cell surface retention of anti-CCR4 antibodies.

Labeled anti-CCR4 antibodies were incubated with CCR4-positive DT40-cells and the decrease of fluorescent signals during the time course in the presence of excessive amounts of the corresponding unlabeled antibodies were recorded using flow cytometry. To prevent rebinding of labeled molecules, the unlabeled 9E10J IgG1 was added to the cells in all experiments. The off-rate (koff) and half-life (t1/2) values for dissociation of the antibody-antigen complexes were interpolated from the standard curves generated by one-phase exponential decay fit of the experimental data as shown in Figure 5a, b.