Treatment with a monoclonal antibody to IL-8 attenuates the pleocytosis inexperimental pneumococcal meningitis in rabbits when given intravenously, but not intracisternally

The role of interleukin (IL)-8 as mediator in the recruitment of leucocytes into the CSF was investigated during experimental pneumococcal meningitis. Rabbits were inoculated intracisternally with approximately 10(6) CFU Stre ptococcus pneumoniae, and treated (i) intravenously with 5 mg of a monoclon al antibody to IL-8 (n = 7) or 5 mg of an isotype control antibody (n = 6); (ii) intracisternally with anti-IL-8, 100 mug (n = 5), 10 mug (n = 4), 1 m ug (n = 4), 0.1 mug (n = 2). Ten rabbits served as untreated control group. Intravenous treatment with anti-IL-8 attenuated the pleocytosis significan tly compared to untreated rabbits (P < 0.04) or rabbits treated with an iso type control antibody (P < 0.02). In contrast, intracisternal treatment wit h anti-IL-8 failed to attenuate the pleocytosis (P > 0.05). These results s how, that IL-8 plays an important role in the recruitment of leucocytes dur ing experimental pneumococcal meningitis, and that the functional activity of IL-8 in this process appears to be on the bloodstream side of the microv ascular endothelium of the brain.