Elimination of blood-derived macrophages inhibits the release of interleukin-1 and the entry of leukocytes into the cerebrospinal fluid in experimental pneumococcal meningitis

Abstract

Parameters of inflammation during pneumococcal meningitis were determined in rabbits after monocyte elimination by dichloromethylene diphosphonate (Cl 2MDP)-containing mannosylated liposomes in comparison with untreated controls. Monocyte depletion reduced the migration of white blood cells into the cerebrospinal fluid (CSF) (medians: 42 versus 2146/mm 3 at 18 h, 323 versus 7413/mm 3 at 24 h p.i., p<0.01). CSF IL-1 β concentrations were lower in depleted animals (379 versus 3282 pg/ml, 24 h p.i., p<0.01), whereas TNF- α concentrations were not different. Monocyte-depleted animals lost body temperature during the experiment carried out in anaesthesia ( p=0.01) indicating that macrophages are necessary for thermogenesis during meningitis.