Abstract
Recombinant human interleukin-2 (IL-2) was found to be strongly adsorbed onto small liposomes (20-50 mm) containing distearoyl phosphatidylcholine (DSPC) or hydrogenated soy bean phosphatidylcholine (HSPC) as a major lipid component. Under optimal conditions most of added IL-2 was attached to the liposomes. Pharmacokinetic studies for IL-2 merely mixed with such liposomes after intravenous administration in BDF1 female mice demonstrated more prolonged blood circulation and higher AUC in various organs except for kidneys in comparison with IL-2 alone. A mixture of IL-2 with DSPC/DSPG (10/1) liposome (Lipo 1-IL2) gave 13- or 18-times higher AUC in liver and spleen, respectively. Lipo 1-IL2 showed enhanced inhibition against hepatic metastases of M5076 intravenously inoculated in mice, when compared with IL-2 alone. This therapeutic effects against metastases in other organs, lung and ovary, were weaker than that in liver. The mixture did not affect liver function GOT or GPT when normal mice were treated with twice the dose showing excellent antitumor effect. This simple preparation with easy use is expected to have potential for increasing therapeutic efficacy against hepatic metastases.
