Therapeutic antibody specific anti-IDs (hybridomas) were screened for high affinity antibodies using an Octet Red 384 (ForteBio, Fremont, CA) label-free molecular interaction analysis instrument. Human IgG Fc biosensors (Cat#18-5060,Forte Bio, Fremont, CA) were incubated in 1X kinetic buffer (Cat# 18-1092, Forte Bio, Fremont, CA) for 60 seconds followed by immobilization of therapeutic antibody (5 µg/mL) onto the sensors for 180 seconds. For the association phase, the biosensors were dipped into wells with anti-idiotype antibodies and one isotype control antibody at 100 nM for 240 seconds. One well containing kinetic buffer only was used as reference/blank control. For the dissociation phase, biosensors were dipped into kinetic buffer for 600 seconds. Binding affinity, related to the equilibrium dissociation constant KD, values were calculated using the Octet Data Analysis HT software (Version 10.0) and a 1:1 binding model was applied for Kinetic fitting. The recommended conditions of full R 2 ≥0.80, and the response>0.01 were used to select for high affinity antibodies.