Peripheral Immune Activation in Alzheimer's Disease

Abstract

In fifty-four patients with Alzheimer's disease [AD (14 males, 40 females, age 77 .1 2: 7.4 years)], free of any infection and twenty-two age-matched healthy controls with normal mental status (9 males, 13 females, age 74.9 ± 9.0 years) serum concentrations of soluble parameters of immune activation including neopterin, 55 kDa-type soluble tumor necrosis factor receptor (sTNF-RSS), soluble interleukin-2 receptor (sIL-2R), immunoglobulins A, M and G, complement components C3 and C4, circulating immune complexes, and soluble CD23 as well as a panel of routine laboratory tests were determined.Compared to controls, significantly higher concentrations of sIL-2R (p < 0.01), neopterin (p < 0.01), sTNF-R55. sCD23 and IgA (all p < O.OS) were found in AD patients. Patients with greater cognitive impairment had higher concentrations of neopterin and sTNF-R55 . An inverse correlation was seen between mini mental state (MMS) and sTNF-R55 (r = -0.43S; P < 0.01) and neopterin (rs = -0.289; P < 0.05). Our data show increased serum concentrations of immune activation markers in patients with AD correlating with the severity of dementia. Increased neopterin concentrations together with increased slNF-R55 and sIL-2R imply a chronic state of peripheral immune activation in the course of AD. Our data underscore previous reports on the effect of anti-inflammatory drugs in therapy and prevention of AD.