Phenotypic characterization of Ewing sarcoma cell lines with monoclonal antibodies

The histogenesis of Ewing sarcoma, the second most frequent bone tumor in humans, remains controversial. Four Ewing cell lines were analyzed by immunological methods. A panel of antibodies directed to T, B, and myelomonocytic markers gave negative results. Surface antigens recognized on Ewing cells were found to be related to the neuroectoderm lineage. Ganglioside GD2, a marker of neuroectodermal tissues and tumors, was present on all lines. These were also stained by the mouse monoclonal antibody HNK-1, which detects a carbohydrate epitope present on several glycoconjugates of the nervous system, including two glycoproteins, the myelin-associated glycoprotein and the neural cell-adhesion molecule (N-CAM), and an acidic glycolipid of the peripheral nervous system. The P61 monoclonal antibody, which reacts with a peptide moiety of N-CAM, and a rabbit antiserum, raised to purified mouse N-CAM and not recognizing the HNK-1-defined epitope, were also reactive. By contrast, all antibodies specific for hematopoietic cell surface antigens were totally negative. Besides these antigenic features, Ewing sarcoma cells are characterized by a specific t(11;22)(q24;q12) translocation also observed in neuroepithelioma, a neuroectodermal tumor, suggesting a possible evolutionary related origin. The recent finding that the human N-CAM gene is located at the vicinity of the breakpoint on chromosome 11 indicates that it might be involved in genetic rearrangements occurring in this region.