Charcoal suspension for tumor labelling modifies macrophage activity in mice

We have previously developed a charcoal suspension for injection into human breast cancers in order to facilitate their location during surgery. We ob served that charcoal particles were ingested by intra and peritumoral macro phages, some of which carried the particles at some distance from the injec tion site. We studied the influence of the formulation parameters of the ch arcoal suspension for intratumoral injection on in vitro and in vivo activa tion and in vivo mobilization of mouse peritoneal macrophages after intra-p eritoneal injection of 2 mt of each preparation. The influence of the charc oal origin (peat vs wood), granulometry, suspension vehicle (water for pare nteral injection, vs saline), concentration and excipients were studied. Mi cronized peat charcoal in water for injection at the highest studied concen tration reduced macrophage activation in vitro and in vivo. However, macrop hage mobilization was weaker than after thioglycolate injection and did not seem to be charcoal dose-dependent. The additives incorporated in the char coal suspension led in vivo to increased peritoneal macrophage activation a nd mobilization (mannitol, and glucose), only increased activation (polysor bate 80 and pluronic F68) or mobilization (dextran 40, egg lecithin, and ca bosil), or inhibited both activation and mobilization (cremophor EL).