Interleukin-6 is not altered in cerebrospinal fluid of first-degree relatives and patients with Alzheimer's disease.

We investigated interleukin-6 (IL-6) levels in cerebrospinal fluid (CSF) of 25 patients with clinically diagnosed sporadic Alzheimer's disease (AD) and 19 healthy control subjects (HC). For comparison 19 clinically healthy subjects with at least one first-degree relative with clinical or autopsy confirmed AD (CF/AD) were examined. CSF levels of IL-6 did not show statistically significant differences between AD patients, CF/AD and HC subjects. There was no correlation between age, gender, age of onset, degree of cognitive impairment, blood-brain barrier dysfunction and IL-6 values. We could not demonstrate altered CSF concentrations of IL-6 that may indicate an inflammatory response or capability to support neuronal survival in the central nervous system (CNS) of first-degree relatives and patients with AD. We suggest that combined measurement of all parameters of the IL-6-receptor complex could yield more insight in a probably altered IL-6 function.