Interleukin‐6 and interleukin‐1 receptor antagonist in acute stroke

Abstract Elevated plasma levels of interleukin‐6 (IL‐6), a key regulator of the acute phase response that includes increased fibrinogen synthesis, have recently been detected in patients with acute stroke. Nevertheless, the role of the acute phase response in stroke has been controversial, with some studies suggesting that preexisting infection accounts for most of the acute phase response. Increased IL‐6 could signal the involvement of antiinflammatory activity, since IL‐6 stimulates the production of endogenous antiinflammatory mediators such as interleukin‐1 receptor antagonist (IL‐1RA). To better understand the interaction of pro‐ and antiinflammatory acute phase processes in brain infarction, plasma levels of IL‐1RA, IL‐6, and acute phase proteins including fibrinogen and c‐reactive protein (CRP) were measured within 4 ± 2 days of onset in 50 patients with acute ischemic stroke and in 20 age‐matched healthy controls. After excluding patients with evidence of infection, both IL‐1RA and IL‐6 were significantly elevated in stoke patients compared with controls ( p <0.0001). IL‐1RA and IL‐6 were both significantly correlated with levels of CRP, p <0.05 and p <0.001, respectively, but not with each other. Levels of IL‐6 and IL‐1RA, together with fibrinogen and CRP were higher in patients with infarcts of greater than 3 cm and lowest in patients with lacunar syndromes. Detection of increased peripheral levels of IL‐1RA, IL‐6, and additional acute phase reactants, including CRP, in acute stroke uncomplicated by infection suggests that an acute phase response to brain infarction occurs and that the magnitude of this response may be related to the volume of infarcted brain.