Prolonged elevation of cytokine levels after human acute ischaemic stroke with evidence of individual variability

Abstract

There is inflammation at the site of pathology in acute ischaemic stroke. In humans there is also elevation of levels of circulating cytokines in the days after stroke. We have previously found increased level of circulating T cells for up to three weeks after stroke. We have now measured cytokine levels for up to three weeks after stroke, looking for evidence of ongoing immune changes after the acute injury. Blood was collected from healthy controls and from subjects with acute ischaemic stroke on day 1, week 1 and week 3 after onset. Levels of interleukin 6 (IL6), interleukin 10 (IL10) and transforming growth factor beta (TGF-β) were measured by ELISA. We compared the cytokine levels in males and females, and correlated levels with stroke type as classified by the Oxfordshire stroke classification and stroke severity assessed by the NIH Stroke Scale. In the total group, levels TGF-β were significantly elevated at day 1. In the total group, levels of IL-6 were significantly elevated at all time-points. Levels of IL-10 were significantly elevated at week 1. The finding of elevated cytokine levels gives further evidence of ongoing immune activation for up to 3 weeks after acute ischaemic stroke. There was only a modest effect of stroke severity on levels of IL-6. There was also variability among individuals.