SELECTIVE TRANSPORT OF BLOOD-BORNE INTERLEUKIN-1-ALPHA INTO THE POSTERIOR DIVISION OF THE SEPTUM OF THE MOUSE-BRAIN

Film autoradiography was used to demonstrate the transport and sites of accumulation of blood-borne radioiodinated interleukin-lct (Il-1 alpha) and other cytokines into the brain after intravenous administration. [I-125]Il-1 alpha, [I-125]Il-1 beta, [I-125]interleukin-1 receptor antagonist (Il-1ra), and [I-125]tumor necrosis factor-alpha (TNF alpha) labeled the choroid plexus and the capillary network 30 min after injection into the blood, suggesting that these areas may serve as sites of blood-to-brain transport. [I-125]Il-1 alpha, but not [I-125]Il-1 beta, [I-125]Il-1ra, [I-125]TNF alpha, or [I-125]interleukin-2 (Il-2), was also found localized to the caudal region of the septal nuclei. Only unlabeled Il-1 alpha was able to inhibit this accumulation. These findings provide further evidence for the passage of select cytokines across the blood-brain barrier (BBB) and are the first to identify a target site within the central nervous system (CNS) for a transported cytokine.