A method for in vitro clearance of mycoplasma from human cell lines.

Rapid and reproducible clearance of mycoplasma contaminating human cell lines was achieved using macrophages and antibiotics. Human peripheral blood monocytes were purified by Percoll density gradient centrifugation and allowed to mature into macrophages by 7 days culture in vitro. To the adherent monolayers of macrophages were added the cells to be cleared. Optimal results were obtained with a macrophage to cell concentration of 100:1, together with 200 micrograms/ml of the antibiotics tylosin and lincomycin. The cleared cells were recovered after 7 days of treatment. Monitoring with the Hoechst 33258 stain demonstrated that cells cleared by this method have remained mycoplasma-free for over 6 months. The method is unlikely to cause cell mutation or to introduce mouse viruses and is effective on both adherent and non-adherent cell lines.