Binding Affinity of Anti-CD137 Antibody

Example 7

Jurkat cells (i.e., an immortalized human T lymphocyte cell line) characterized by stable, over-expression of hCD137 were plated at 20,000 cells/well and stained with a titration of primary murine anti-CD137 antibody BBK2 (BBK2-mIgG1) for 4 hours at 4° C. Secondary anti-mouse AF488 stain, at a constant amount, was added for 30 minutes at 4° C. After washing, plates were run on a flow cytometer and binding of BBK2-mIgG1 (and the negative control, i.e., mIgG1) was determined based on geometric mean fluorescence intensity in the AF488 channel. Results from these assays are provided in FIGS. 1A and B.

As shown in FIGS. 1A and 1B, the murine BBK2 antibody binds to human T cells (i.e. CD137-expressing Jurkat cells), with an EC₅₀=35 pM.