IDENTITY OF ORIGINAL AND LATE PASSAGE DAMI MEGAKARYOCYTES WITH HEL ERYTHROLEUKEMIA-CELLS SHOWN BY COMBINED CYTOGENETICS AND DNA-FINGERPRINTING

During routine authentication checks, we noticed untoward karyotypic s imilarities between late-passage stocks of the Dami megakaryocyte and HEL erythroleukemia cell lines. Genetic identity of Dami with HEL was demonstrated by DNA fingerprinting with a (gtg)(5) multilocus probe an d confirmed for earlier passages of Dami deposited by its originators with the ATCC, as initial passage stocks of Dami are no longer availab le for comparison, we investigated whether cross-contamination by HEL was more likely Po have occurred during Dami's establishment or subseq uently, by karyotyping currently available stocks of both cell lines f or comparison with that originally reported for Dami. We found that th e karyotype of current stocks of Dami overwhelmingly resembles that de scribed in the original report, having retained at least 16/18 structu ral chromosome rearrangements as described therein, cf. 12/20 shared b y current stocks of Dami and HEL. HEL's antecedence is shown by the re tention of normal homologs of chromosomes, 6, 18, and 21 - all rearran ged in Dami. These results confirm the identity of current and early p assage stocks of Dami and their common origin by cross-contamination w ith HEL which had occurred by July 1987, a year prior to publication. Thus, most, if not all, studies using Dami are likely to have employed HEL instead and may require reappraisal.