HUMAN PAPILLOMAVIRUS TYPE-18 DNA IN SO-CALLED HEP-2-CELLS, KB-CELLS AND FL-CELLS - FURTHER EVIDENCE THAT THESE CELLS ARE HELA-CELL DERIVATIVES

The contamination of HeLa cells into many culture cells has been suspe cted. We detected HPV type 18 DNA in two HeLa cell sublines, Hep-2 lar yngeal cancer and KB oral cancer cell lines as well as FL cell line de rived from normal amniotic membrane which have been extensively used s o far in experimental virology. On the other hand, we detected HPV typ e 18 DNA neither in other epithelial cell lines nor in fibroblastic hu man embryonic cells. The digestion analysis with several restriction e nzymes of the HPV type 18 DNA in HeLa, Hep-2, KB and FL cell lines wer e almost the same. The molecular size of episomal DNA could not be dem onstrated by digestion of these DNAs with XhoI, a non-cut enzyme for H PV type 18 DNA, suggesting all HPV types 18 DNA were integrated. Inter estingly enough, the HPV type 18 specific DNA in these cells was cleav ed into two fragments with another non-cut enzymes, B glII and HindIII , suggesting the presence of a single cutting site for each enzymes pr esumably generated by rearrangements or mutations. These results provi de further evidence that the so-called Hep-2, KB and FL cells are all HeLa cell derivatives.