PARTIAL INHIBITION OF AT-EAE BY AN ANTIBODY TO ICAM-1 - CLINICO-HISTOLOGICAL AND MRI STUDIES

The role of quantitative proton magnetic resonance imaging (MRI) for t he evaluation of immunopathological lesions in the CNS was studied in adoptively transferred experimental allergic encephalomyelitis (AT-EAE ). We utilized a recently established treatment model, inhibition of t he cell adhesion molecule ICAM-1 by the monoclonal antibody 1A-29. The animals were scanned on days 3, 5 and 7 after injection of encephalit ogenic T-cells, before and after bolus injection of Gd-DTPA by perform ing T1-measurements to assess the integrity of the blood-brain barrier (BBB). On day 7, immunohistochemistry was performed looking for T-cel ls, activated macrophages, and albumin staining. There was clinical ev idence of partial inhibition of AT-EAE in rats treated with antibodies against ICAM-1. This finding was in line with a significantly reduced number of T-cells in the medulla. However, the number of activated ma crophages and the distribution of albumin did not differ from untreate d AT-EAE animals. The histological findings are in agreement with the MRT data before and after Gd-DTPA injection which were similar in trea ted and untreated AT-EAE rats on day 3 and 5. On day 7 after Gd-DTPA i njection there was evidence of a delayed breakdown of the BBB in the t reated rats. The observation of a dissociation of clinical and MRI fin dings, especially evidence of Gd-enhancement despite clinical improvem ent, may be important in the context of interpreting MRI studies in MS patients in treatment trials.