Detection and characterization of antibodies to PEG-IFN-α2b using surface plasmon resonance

Some patients treated with type I interferon (IFN) preparations develop neutralizing antibodies that may abrogate any clinical benefit. We have a new complex of polyethylene glycol(12000) and IFN-alpha 2b (PEG-IFN-alpha 2b) in clinical trials and need to be able to detect any antibodies formed specifically against the complex, We have, therefore, devised a method based on measurement of surface plasmon resonance (SPR) in the BIACORE 2000(TM) apparatus. PEG-IFN-alpha 2b is anchored to one flow cell on the sensor chip, IFN-alpha 2b to another, and PEG to a third. A 20 mu l serum sample flows in turn through the three cells, which are optically scanned. Any antibodies in the serum bind to the corresponding immobilized antigen, and a change in the optical signal is generated. With appropriate specific reagents, their immunoglobulin isotype can be similarly established. The automated assay can quickly test numerous sera. Very little serum is needed, and the assay is reliable and precise and can detect low-affinity antibodies.