Derivation of stable polyploid sublines from a hyperdiploid Ehrlich ascites carcinoma.

Summary Repeatable experimental production of polyploid sublines from the hyper-diploid Ehrlich ascites carcinoma has been achieved. After intraperitoneal injection of low cell dosage or starved cells or refrigerated cells into Swiss female adults, primary ascites often failed to develop. The secondary ascites infiltrating from the subcutaneous solid tumor nodules at the inoculation site contained from 60 to 95 per cent of polyploid cells. From these ascites, stable hyper-tetraploid sublines were established and maintained in serial transfer for over 20 weeks. The modal chromosome number of the derivative sublines is at 90–92, exactly twice that of 45–46, characterizing the original hyper-diploid Ehrlich. The mechanisms involved in these shifts of ploidy are discussed from the point of view of “immunoselection.”