Ewing's sarcoma. Characterization in established cultures and evidence of its histogenesis

We have studied the ultrastructure and collagen biosynthetic profiles of three cultured lines of Ewing's sarcoma (ES) to better understand the histogenesis of this tumor. The histology and ultrastructure of the original tumors were characteristic of ES. Light and electron microscopic appearance of the cell lines and of tumors formed in nude mice from injection of these lines were similar to the native tumors. Isozyme studies of the ES cell lines demonstrated that they were not HeLa and were different from other known cell lines. Collagen profiles performed by immunofluorescence, polyacrylamide gel electrophoresis, and immunoprecipitation showed conclusively that ES in tissue culture produces collagen types I, III, and IV. This collagen profile coupled with the morphologic and ultrastructure features of the ES cell lines leads us to conclude that Ewing's sarcoma is derived from a multipotential primitive mesenchymal cell, uncommitted to osteoblastic, fibroblastic, or endothelial origin.