Serial analysis of peripheral blood T-cell phenotypes and myelin basic protein reactivity in experimental allergic encephalomyelitis.

We have serially analyzed peripheral blood T-cell phenotypes and reactivity to myelin basic protein (MBP) during the course of acute experimental allergic encephalomyelitis (EAE) in the Lewis rat and have correlated changes with the onset of clinical disease. A reduction in total T cells (W3/13+), due primarily to a reduced helper/inducer (W3/25+) subpopulation, preceded the onset of EAE. Circulating MBP-reactive lymphocytes were only transiently present in the blood at the time EAE was clinically evident. Our findings demonstrate that in EAE, immunologic abnormalities in the peripheral blood are transient and can begin before clinical disease is evident.