Increased Cytokine Release from Peripheral Blood Cells after Acute Stroke

Abstract

Cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α can play pathogenetic or protective roles in stroke. They are increased in the brain after experimental ischemia and in the CSF of patients with stroke. However, their presence in the periphery is still controversial. To determine the source and time-course of cytokines in blood of stroke patients, IL-6 and TNF-α release from blood cells and serum levels were determined in 40 patients on days 1 through 2, 4, 10, 30, and 90 after stroke. Twenty healthy age-matched volunteers were used as controls. IL-6 and TNF-α release from stimulated blood cells was increased in stroke patients, compared to controls. A peak response (+224%) was observed at day 4 for IL-6, while TNF-α release was largely and significantly increased (about three-fold compared to controls) from day 1 to 2 until day 90 after stroke. The increase in IL-6 release was significantly higher in ischemic, compared to hemorragic strokes, at days 1 and 4. Circulating IL-6 was increased at each time point. The ischemic processes in the CNS induces a long-lasting activation of IL-6 and TNF-α production in peripheral blood cells, which are a major source of serum cytokines after stroke.