The monoclonal antibody ART 18 directed to the rat interleukin-2 receptor (IL-2 R) was administered to Lewis rats immediately prior to and/or on consecutive days after adoptive transfer of autoreactive P2-T line lymphocytes. The effects of ART 18 and sham treatment on the development of adoptive transfer--experimental autoimmune neuritis (AT-EAN) were assessed by clinical inspection, serial electrophysiological monitoring, and semiquantitative histomorphological analysis. Early injection of ART 18 suppressed AT-EAN while treatment after appearance of clinical signs did not. Since the IL-2 R is expressed exclusively on proliferating T cells activated by antigen, the in vivo application of an IL-2 R-targeted monoclonal antibody allows for more selective immunosuppression of experimental autoimmune disease of the peripheral nervous system than has previously been achieved.