Immunoregulation of passively induced allergic encephalomyelitis.

Experimental allergic encephalomyelitis (EAE) can be readily induced passively by transfer of lymphocytes from neuroantigen immunized rats to naive recipients. This passively induced disease runs an acute, monophasic, self-limiting course, much the same as is usually seen in actively induced diseases. Here we examine the mechanisms regulating passive EAE. We report that splenectomy, thymectomy, and increasing age of recipients, manipulations which have been reported to influence recovery from actively induced EAE, have no effect on passively induced disease. EAE effector cells are not inactivated when transferred into recipients that have been actively sensitized and are beginning their recovery from clinical signs; this being a time when recovery associated suppressor cells are thought to be present. Finally, in the absence of suppressor T cells in both the recipient and in the transfer cell population, recovery from passive EAE still occurs. We conclude that suppressor T cells play no role in regulating passively induced EAE.