Is it possible to maintain macrophage depletion for longer periods of time?
– Under normal conditions i.e. in the absence of activation by some microbial products, macrophage populations such as Kupffer cells in the liver and red pulp macrophages in the spleen start to repopulate their compartments after ca. one week. – Other macrophage populations such as marginal metallophilic macrophages and marginal zone macrophages in the spleen (after intravenous injection) and macrophages in lymph nodes (after subcutaneous injection in their draining areas) remain absent for much longer periods of time (see relevant literature under manuscripts). – In order to achieve a prolonged macrophage depletion in SCID mice, Fraser et al (Blood, 86; 183-192, 1995) tried several injection schedules in which one undiluted injection of clodronate liposomes was followed by subsequent diluted doses of clodronate liposomes each 5-7 days. – However one should keep in mind that macrophages regulate functional aspects of various non-phagocytic cells. As a consequence, their long term absen
