Lecithinization of IL-6 enhances its thrombopoietic activity in mice

This study was conducted to assess the merit of lecithinization of recombinant human interleukin-6 (IL-6) as a drug delivery system. IL-6 was lecithinized by covalently binding it with a phosphatidylcholine (lecithin, PC) derivative. The in-vivo thrombopoietic potency of lecithinized IL-6 (PC-IL-6) was greater than that of native IL-6 when administered 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 activity, the former stimulated less production of IgG1, a marker of the adverse effects of IL-6, than did the latter. Furthermore, PC-IL-6 persisted 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.