CXCL8 and Decreased total leukocyte count: Our results suggest that a novel feedback mechanism involving blood derived leukocytes that control the CSF production of IL-8 as a local chemotactic signal, which is accordance with findings from a rat pneumonia model, where MIP-2, the IL-8 analog in rats, was higher in alveolar fluid during cyclophosphamide-induced leukopenia [26].