IMMUNOCYTOCHEMICAL LABELING OF AEROBIC AND HYPOXIC MAMMALIAN-CELLS USING A PLATINATED DERIVATIVE OF EF5

The monoclonal antibody ELK3-51 was previously developed to detect add ucts of the 2-nitroimidazole EF5. Direct immunofluorescence was used t o detect adducts of EF5 or of a platinated derivative cis-[PtCl2(NH3)E F5] in SCCVII cells treated under aerobic or hypoxic conditions. Fluor escence measurements of these cells using both image and flow cylometr ic methods were compared, giving similar profiles. Platination signifi cantly decreased immunofluorescence levels (similar to 4-fold less tha n EF5) after 3h in hypoxia, but also increased levels after exposure i n air (similar to 1.5 x) such that the hypoxic ratio decreased from si milar to 50 to similar to 13. Platinated EF5 also showed significantly greater cytotoxicity than its parent in both aerobic and hypoxic cell s. These results are consistent with targeting of EF5 to DNA, which wa s confirmed qualitatively by confocal microscopy.