Figure 5.

Viral challenge increases temporal pattern of recruitment of neutrophils to the inflamed central nervous system (CNS). Illustrations show schematic representations of the pattern of neutrophil recruitment to the challenged brain (* represents the microinjection site in the brain for all animals and time points). The microinjection of vehicle, in the presence of intravenous AdLuc (5 × 10⁹ CFU) did not cause recruitment of neutrophils to the brain at any time point (left column). The microinjection of IL-1β in the presence of intravenous vehicle (central column) caused bilateral meningitis, and the recruitment of neutrophils to the injected hemisphere in large numbers at 12 hours. By 3 days, the area over which neutrophil recruitment was occurring, and the numbers recruited were decreased. By 7 days, only isolated cells were observable. When the microinjection of IL-1β was combined with intravenous challenge with AdLuc (right column), neutrophil recruitment was widespread, covering both hemispheres at 12 hours post-injection, with significantly more cells recruited in the contralateral hemisphere than after IL-1β/vehicle. By 3 days, the area over which neutrophil recruitment was occurring was reduced, although again greater than in animals receiving intravenous vehicle. By 7 days, recruitment was near basal levels, although some meningitis was still evident. Intravenous injections are indicated by italic text. CFU, colony-forming unit.