Expression of interleukin-1β in lipopolysaccharide stimulated monocytes derived from patients with aneurysmal subarachnoid hemorrhage is correlated with cerebral vasospasm

Cerebral arterial vasospasm is a frequent complication after aneurysmal subarachnoid hemorrhage (SAH). Immunological activation may affect the development of vasospasm. This study measured the cytokines released from lipopolysaccharide-stimulated monocytes of SAH patients. We measured cerebral artery diameters before and after surgery for SAH. The activation index of interleukin-1β (IL-1β), but not tumor necrosis factor-α (TNF-α), was higher in patients with symptomatic vasospasm (5.6±1.7; n=11) than in patients without (1.8±0.4; n=11) (P=0.039). Furthermore, the IL-1β activation index was correlated with the degree of the postoperative angiographic vasospasm (correlation coefficient=-0.66, P=0.007). Individual variation in systemic immune activation, measured by monocyte-derived IL-1β expression levels after stimulation, may be associated with the development of vasospasm after aneurysmal SAH.