Selection and characterization of human monoclonal antibodies against Abrin by phage display

Abrin is a highly potent and lethal type II ribosome inactivating toxin that may be used as a biological warfare agent. To date, no human anti-Abrin antibodies have yet to be reported. Herein, we describe the selection and characterization of two human monoclonal antibodies, termed E12 and RF12, which are capable of binding native Abrin with high affinity and specificity. Through surface plasmon resonance studies, we have determined the association and dissociation rate constants and the cross-reactivity for both antibodies. In our developed Biacore-based Abrin detection system, the limit of detection of antibodies E12 and RF12 is 35 and 75 ng/mL, respectively. These concentrations are about 5 × 104-fold lower than the extrapolated Abrin human LD50. In sum, our data demonstrated the power of human antibody phage display libraries and the promise of these antibodies as detection devices for Abrin.