Is it possible to deplete macrophage precursors?
– Whereas intravenously injected clodronate liposomes have no access to mature macrophages in e.g. the gut, due to the fact that liposomes are not able to cross the vascular endothelium of capillaries, Galeazzi et al. (Am J. Physiol. 278 G259-G265, 2000, see also under manuscripts) described the effects of intravenously injected clodronate liposomes on the inflammation induced recruitment and infiltration of F4/80 positive cells into the jejunum of mice. With respect to this question, the following is important: Precursors of macrophages (monocytes) recruited to e.g. inflammatory areas seem to be depleted by clodronate liposomes in the circulation. In such cases, several injections with clodronate liposomes have to be given shortly after each other, since 1. liposomes do not survive for long in the circulation and 2. new monocytes can be recruited within a relatively (compared to mature macrophages) short time. In the studies of Galeazzi et al., clodronate liposomes were given 4 hrs. b
