ENDOCYTOSIS OF POLY(ETHYLENE OXIDE)-MODIFIED LIPOSOME BY HUMAN LYMPHOBLASTOID-CELLS

Egg PC liposome as reconstituted with poly(ethylene oxide)-bearing lip id (coded as PEG-lipid (n = 15)) was remarkably endocytosed by Jurkat cell, which was a lymphoblastoma derived from human T cell. To confirm the endocytosis, two kinds of fluorescent probes (FITC-dextran and oc tadecyl rhodamine B) were employed. The former was loaded in the aqueo us phase of the liposome, while the latter was embedded in the liposom al membrane. Both probes were found coincidentally at the same site in the cytosol, clearly suggesting that whole Liposome entered the cell. The endocytosis was most obvious when PEO-lipid (n = 15) was employed above 50 mol%. FITC-Dextran entered the cell was found small dots in the cell, not dispersive. Even when octadecyl rhodamine B was used, no membrane fluorescence was observed at all. The uptake closely related to the cell metabolism as affected by the culture temperature and ser um in the incubation medium. Furthermore, the addition of cytochalasin B completely prohibited the cell uptake of liposomes.