Abstract
Monoclonal antibodies (mAbs) BW 625 and BW 704, of the IgG3 isotype, bound to immunochemically indistinguishable epitopes on ganglioside II3(Neu-Ac)2-GgOse3-Cer. Despite this fact the mAbs showed a differential binding pattern on human glioma cell lines i.e. immunohistochemical data indicate that the detected epitopes are not identical. Furthermore, either mAb is able to mediate the antibody-dependent cellular cytotoxicity reaction (ADCC) and the human-complement-dependent cytotoxicity reaction (CDC) with epitope-expressing tumor cells. All cryopreserved tissue specimens from gliomas and neuroblastomas were immunohistochemically stained, whereas the other small round cell tumors of childhood, as well as melanomas and small-cell lung carcinomas, were essentially negative. Positive staining of normal cryopreserved tissues was restricted to amyelinic axons, Hassal's bodies and some connective tissue fibers in thymus and the tegumentary epithelium of skin. The high selectivity of mAb BW 704 for gliomas and neuroblastomas, the lack of cross-reactivity with major tissues and the strong ADCC and CDC potential argue for the use of mAb BW 704 in immunotherapy of neuroblastomas and gliomas.