Increased plasma levels of interleukin-1, interleukin-6 and alpha-1-antichymotrypsin in patients with Alzheimer's disease: peripheral inflammation orsignals from the brain?

Plasma concentrations of interleukin-1 beta (IL-1 beta), interleukin-6 (IL- 6), C reactive protein (CRP) and alpha-1-antichymotrypsin (ACT) in 145 pati ents with probable Alzheimer's disease (AD) and 51 non-demented controls we re measured. To investigate the cellular activation of peripheral immune sy stem, plasma levels of neopterin were also investigated. Plasma levels of I L-1 were detectable in 17 patients with AD (13%) and only in one control (2 %) and average levels of IL-1 were higher in AD patients than in controls ( p < 0.001). IL-6 plasma levels were detectable in a higher proportion of AD and controls (53% and 27%, respectively), and were increased in patients w ith AD (p < 0.001). Plasma levels of ACT were increased in patients with AD (p < 0.001) and CRP levels were in the normal range. Plasma levels of neop terin were slightly lower in AD patients than in controls, but differences were not statistically significant. No significant correlation was observed between IL-1 and IL-6 levels or neopterin and cytokine levels in plasma fr om AD patients. Plasma levels of ACT negatively correlated with cognitive p erformances, as assessed by the mini mental state examination (MMSE; R = -0 .26, p < 0.02) and positively correlated with the global deterioration stat e (GDS) of AD patients (R = 0.30, p < 0.007). Present findings suggested th at detectable levels of circulating cytokines and increased ACT might not b e derived by activation of peripheral immune system of AD patients. Detecti on of these molecules might be used for monitoring the progression of brain inflammation associated with AD. (C) 2000 Published by Elsevier Science B. V. All rights reserved.