ELECTROPORATION AND DNA-DEPENDENT CELL-DEATH IN MURINE MACROPHAGES

The difficulty of transfecting primary macrophages and macrophage cell lines has meant that relatively few studies on regulation of gene exp ression have been performed in these cells. This study has optimized a n electroporation procedure for the macrophage cell line RAW 264, but shows that introduction of DNA into the cytoplasm of primary macrophag es by electroporation is toxic to the cells. It is proposed that this cell death may have a physiological role in defence against certain vi ral infections which result in accumulation of cytoplasmic DNA. RAW 26 4 cells were efficiently transfected by electroporation, but electropo rated bone marrow derived macrophages (BMM) showed large scale cell de ath over a period of 12 h. Electroporation without DNA was not toxic a nd DNase treatment of samples before transfection prevented cell death . The toxicity of DNA was concentration-dependent and sequence-indepen dent. Synthetic, genomic and plasmid DNA all caused cell death. This s ensitivity to DNA seems to be distinct from the antiviral state induce d by double-stranded RNA and may be part of an uncharacterized viral d efence system.