MAGNETIC-RESONANCE-IMAGING INVESTIGATION OF BLOOD-BRAIN-BARRIER DAMAGE IN ADOPTIVE TRANSFER EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS

Recent advances in fast magnetic resonance imaging (MRI) techniques ha ve allowed quantification of parameters such as Tl relaxation time, wh ich can be modified by changes in the water content of a tissue. We ha ve used this new method to study the evolution of blood-brain barrier (BBB) changes after adoptive transfer of MBP-specific (AT-EAE) and ova lbumin-specific T cell lines in Lewis rats. Measurable changes in Tl r elaxation time suggesting widespread increase in BBB permeability were found, starting on day 3 post inoculation (p.i.), in the midbrain and brainstem of AT-EAE rats. In addition, we noted a significant decreas e in Tl relaxation time before injection of a paramagnetic agent, in t he cisternal cerebrospinal fluid (CSF) of diseased animals, starting o n day 5 p.i. In vitro measurement of Tl in CSF containing various conc entrations of albumin, IgM and glucose showed that, at physiological c oncentrations, a Tl decrease is mainly associated with an increase in albumin concentration. A moderate increase in BBB and blood-CSF barrie r permeability was found as early as 4-8 h p.i., in rats injected with MBP-specific as in animals injected with ovalbumin-specific T cell li nes, suggesting a non-specific mechanism. Experimental MRI may become a powerful tool to sequentially analyse changes in barrier dynamics, f or example following pharmacological intervention.