A classification on the basis of time-course effect is proposed to describe
the pleiotropic actions of interleukin-1 (IL-1) on the central nervous sys
tem (CNS); two main time-frames, minutes-to-days and days-to-years, are dis
tinguished The former includes the central aspects of acute-phase response
with fever, altered food and rvatcr intake, sleepiness, sickness behaviour
and neuroendocrine chang es. Apart from stress response triggered by immune
-inflammatory stimuli, the concept that IL-1 mediates other types of stress
is also reviewed, showing that the cytokine may have a role in mediating h
ypothalmic responses to restrain stress and nociceptive stimuli. The days-t
o-years time-frame includes several CNS disorders accompanied by inappropri
ate and/or sustainedly elevated IL-beta production: ischaemia, Alzheimer's
disease, HIV-related dementia and experimental allergic encephalomyelitis-m
ultiple sclerosis. In all cases, IL-beta is not envisioned as an aetiologic
al factor, but it contributes significantly to the maintenance of disease s
tate. Current and perspective therapeutic approaches involving the modulati
on of IL-beta production and effects ale briefly discussed.