Figure 1.

Cell-binding assays evaluating the absolute (counts per minute [cpm]) binding of 1F5-B10 labeled with either ²¹¹At or ¹²⁵I with or without unlabeled blocking antibodies using Ramos and Jurkat cells confirm the antigen-specific cell binding of radiolabeled 1F5-B10 conjugates. (A) [²¹¹At]1F5-B10 binding to Ramos cells was blocked by preincubation with unlabeled anti-CD20 antibodies (2321.0 ± 475.1 vs 409.0 ± 27.5 CPM; 82% blocking). (B) Similar blocking was also observed when the 1F5-B10 was labeled with ¹²⁵I (14 642 ± 3621 vs 679 ± 60.6 CPM; 95% blocking). No difference was seen between the binding of 1F5-B10 antibody to the CD20-negative Jurkat cells in the presence or absence of blocking anti-CD20 antibodies. PBS, phosphate-buffered saline.