Autoantibody potential of cancer therapeutic monoclonal antibodies.

We and others have reported that multiple autoantibodies are unmasked in human polyclonal antibody preparations after exposure to physiological oxidizing agents (hemin) or electromotive force. We now have asked if oxidation unmasks autoantibody reactivities in monoclonal antibodies (mAb). To do this, we have studied 9 FDA approved mAb used therapeutically, including 4 chimeric, 4 humanized and 1 chemically modified chimeric Fab that were exposed to the physiological oxidizing agent hemin at 36 degrees C for 20 hr.