Murine anti-cytomegalovirus monoclonal antibodies with autoreactivity

Certain murine monoclonal antibodies (mAb) raised against structural proteins of mouse cytomegalovirus (MCMV) display distinct patterns of multiple organ-autoreactivity in addition to their viral specificities. We analysed the autoreactivity of five such mAb by immunoperoxidase histochemistry, western immunoblot and enzyme-linked immunosorbent assay (ELISA). Four mAb recognized cellular autoantigens in the salivary gland, lung, heart, liver, kidney, ileum, striated muscle and brain, as detected by immunoperoxidase histochemistry. However, the mAb showed different specificities for nuclear, cytoplasmic and surface membrane antigens on various cell types in addition to common autoreactivities. Immunoblot analyses showed that some of the mAb recognized polypeptides of various molecular weights obtained from 100,000 g supernatants of normal BALB/c liver, brain, striated and cardiac muscle homogenates. Reactivity of the mAb with a 200,000 molecular weight (MW) polypeptide was similar to our previous finding of the reaction of late immune polyclonal sera with a 200,000 MW polypeptide, the heavy chain of myosin. The mAb reacted to the cardiac isoform of myosin as determined by ELISA and immunoblot. Reactivity of mAb with cardiac myosin, as detected by immunoblot, was removed by absorption with cardiac myosin and recovered in the eluate. However, cardiac myosin used in a competitive inhibition ELISA did not abrogate the reactivity of the mAb with MCMV antigens. These anti-MCMV mAb appear to be multispecific for both virus and self-antigens, including cardiac myosin, and possibly recognize these different antigens through partly similar or distinct antigen-binding sites.