SUPPRESSION OF ACUTE EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS BY THE SYNTHETIC SEX-HORMONE 17-ALPHA-ETHINYLESTRADIOL - AN IMMUNOLOGICAL STUDY IN THE LEWIS RAT

Induction of experimental allergic encephalomyelitis (EAE) in female L ewis rats led to the well-known clinical symptoms and histological sig ns. Treatment with the synthetic estrogen 17-alpha-ethinylestradiol (E E) from day -4 before induction until day 21 after induction resulted in partial suppression of these signs and symptoms. Analysis of the pe ripheral blood leukocyte (sub)populations in these treated animals ind icated some remarkable changes. However, these changes were also obser ved without EE treatment. EE treatment of EAE rats resulted in a signi ficant decrease of the relative weights of both thymus and spleen, whi ch changes however were not reflected in the peripheral blood. Apparen tly the effects of EE treatment on EAE in the present experiments indi cate an action locally at the site of the EAE lesion and do not seem t o be mediated by gross changes in the levels of peripheral blood leuko cytes.