Abstract
We and a Dutch group have recently reported the accelerated blood clearance (ABC) phenomenon upon repeated injection of PEGylated liposomes, that is the enhanced accumulation of PEGylated liposomes in liver and consequently rapidly cleared the liposomes from blood circulation. The phenomenon is a general characteristic of liposomes and the induction of the phenomenon depends on the physicochemical property and dose of liposomes and animal species. In addition, our study indicated that the IgM secreted in response to first dose is involved in the occurrence of the phenomenon. In this article, our and a Dutch group's recent results related to the ABC phenomenon were described.