LECITHINIZATION OF IL-6 ENHANCES ITS THROMBOPOIETIC ACTIVITY IN MICE

This study was conducted to assess the merit of lecithinization of rec ombinant human interleukin-6 (IL-6) as a drug delivery system. IL-6 wa s lecithinized by covalently binding it with a phosphatidylcholine (le cithin, PC) derivative. The in-vivo thrombopoietic potency of lecithin ized IL-6 (PC-IL-6) was greater than that of native IL-6 when administ ered subcutaneously, although the in-vitro bioactivity of PC-IL-6 was markedly reduced by lecithinization. When PC-IL-6 and native IL-6 were given in doses that produced the same level of thrombopoietic activit y, the former stimulated less production of IgG(1), a marker of the ad verse effects of IL-6, than did the latter. Furthermore, PC-IL-6 persi sted in the blood longer than native IL-6. Based on the above, PC-IL-6 appears to be useful as a drug delivery system and may also be useful in the treatment of drug-induced thrombocytopenia.