Resolution of cutaneous inflammation after local elimination of macrophages

We constructed an immunotoxin, composed of an antibody directed against the high-affinity IgG receptor CD64 and Ricin-A, with the aim of resolving chr onic inflammation through elimination of activated macrophages, In vitro, t his immunotoxin proved very efficient in inducing apoptosis in activated ma crophages, leaving resting and low CD64-expressing macrophages unaffected. We examined the activity of our immunotoxin in a sodium lauryl sulfate (SLS )-induced cutaneous inflammation model, using transgenic mice expressing hu man CD64. Upon intradermal injection of the immunotoxin (IT), cutaneous inf lammation resolved in 24 h. This was demonstrated histologically by clearan ce of all CD64-expressing macrophages, followed by clearance of other infla mmatory cells. Clinical parameters associated with inflammation, such as lo cal skin temperature and vasodilation, also decreased.