Autologous and Homologous Implantation of Human Cells Transformed In Vitro by Simian Virus 40

The formation of nodules after homologous and autologous implantation of cells from simian virus 40 (SV40) transformed human tissue culture could be correlated with the stages of the transformation process, number of cells implanted, and possibly the presence of infectious virus in the implants. No nodules were formed after homologous implantation of 5 × 106 cells from cultures during the early stages of the transformation process, whereas the same number of cells caused growth of nodules when obtained from cultures in the late transformation stage when production of infectious SV40 had ceased. Usually the homologous implantation of 5 × 106 HeLa cells caused nodules to form. Nodules brought about by HeLa and SV40-transformed cells eventually regressed, with the time required for regression somewhat greater for the HeLa cells. Judging by the results of homologous implantation, HeLa cells and late passage, virus-free, SV40-transformed cells had a comparable neoplastic potential. Histologically, nodules produced by SV40-transformed human cells were sarcomas (fibrosarcomas?). Transformed cells could be recovered from biopsied nodules if they were cultivated in vitro, and reimplantation of the cultured cells again caused growth of nodules. Autologous implantation of SV40-transformed cells seemed to cause growth of nodules in the 2 cases studied. Re-exposure to autologous implants was followed by a second type of reaction, indicating that these cells may have acquired new antigenic properties.