Induction of apoptosis in WEHI 231 cells by cationic liposomes

Purpose, Liposomes are of considerable interest as drug carriers and immuno adjuvants, However, few investigators have studied the changes exerted by l iposomes in the cells with which they interact. The purpose of this study w as to investigate whether liposomes induce apoptosis in B cells. Methods. The mouse immature B cell line WEHI 231 cells and mouse splenic B cells were treated with liposomes, and the induction of apoptosis; was eval uated by monitoring changes in DNA content, DNA fragmentation and chromatin condensation by flow cytometry agarose gel electrophoresis and by morpholo gical investigation. Results, Cationic liposomes induced apoptosis in WEHI 231 cells, but neutra l and anionic liposomes did not. A contact time of 30 min between WEHI 231 cells and cationic liposomes was sufficient to induce apoptosis, and 80% of the cells showed hypodiploid DNA content. Apoptosis induced by cationic li posomes composed of stearylamine was inhibited by addition of the oxidant s cavenger, N-acetyl-cysteine. Conclusions. Cationic liposomes induced apoptosis in WEHI 231 cells, and th e production of reactive oxygen species is important in the regulation of a poptosis induced by cationic lipusomes. It is well known that cationic lipo somes show cytotoxicity, and apoptosis may be one of the causes of this tox icity.