title: Conversion of a melanoma cell line from an HLA class II positive to negative phenotype after treatment with anti-mycoplasma drugs.
abstract: An HLA class II-positive melanoma cell line, DU-Mel 17, expressing both DR and DQ was shown to be contaminated with Mycoplasma hyorhinis. After treatment of the cell line with anti-mycoplasma drugs (a tetracycline derivative and a pleuromutilin), both DR and DQ expression on the cell surface, as well as DR alpha mRNA, were greatly decreased and the cells were rendered mycoplasma-free. Interestingly, drug-treated cells became resistant to geneticin, an unrelated drug. To test whether drug treatment or elimination of mycoplasma caused the abolition of class II expression, contaminated DU-Mel 17 cells were inoculated into peritoneal cavities of nude mice and later removed upon growth of a solid tumor. The cells were shown to be mycoplasma-free, and they expressed DR alpha mRNA, as well as DR and DQ proteins on their surfaces. Although it appears that the drugs were responsible for abating class II molecule expression in DU-Mel 17 cells, the identical drug-treatment regimen on a class II-positive, mycoplasma-free B cell line did not alter DR alpha mRNA or class II protein levels. Based on restriction fragment lengths, the DR alpha gene appeared to be grossly intact after drug treatment, and alterations in methylation patterns were not observed. These studies indicate that anti-mycoplasma treatment of DU-Mel 17 cells resulted in selection of a class II-negative, drug-resistant clone(s). Such treatment may result in a phenotype that is divergent from the parental cell line in one or more characteristics.
authors.affiliation: Department of Microbiology and Immunology, Duke University Medical Center, Durham, North Carolina 27710.
authors.forename: M N
authors.initials: MN
authors.lastname: Carrington
authors.forename: F E
authors.initials: FE
authors.lastname: Ward
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004352:Drug Resistance, Microbial / Q000235:genetics; D006681:HLA-D Antigens / Q000235:genetics*; D006801:Humans; D008545:Melanoma / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D009174:Mycoplasma / Q000187:drug effects / Q000276:immunology* / Q000302:isolation & purification; D010641:Phenotype; D012641:Selection, Genetic; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000276:immunology / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D006681:HLA-D Antigens