Cerebrospinal fluid interleukin-1 beta (IL-1 beta) in Alzheimer's disease and neurological disorders.

Recent studies indicate that patients with Alzheimer's disease (AD) exhibit an immune dysfunction at the central and peripheral levels. We have studied the concentration of IL-1 beta in the cerebrospinal fluid (CSF) of patients with AD, multi-infarct dementia (MID), normal pressure hydrocephalus (NPH), and multiple sclerosis (MS). CSF IL-1 beta levels were significantly higher in AD (131 +/- 17.33 pg/ml) than in MID (79.71 +/- 24.37 pg/ml, p less than 0.01), NPH (84.75 +/- 23.17 pg/ml, p less than 0.01), and MS (79.4 +/- 10.23 pg/ml, p less than 0.01). In patients with neurological disorders CSF IL-1 beta levels showed a progressive increase with age (r = +0.49, p less than 0.015). The concentration of IL-1 beta in CSF of demented patients correlated with mental deterioration (r = -0.476). According to these results we postulate that high levels of central IL-1 beta in AD might reflect a reactive neuroimmune response to: (a) abnormal epitopes exposed by lesioned neurons, (b) reactive microglia activated by exogenous and/or endogenous factors and (c) endogenous neurotrophic activation.