The influence of cyclosporin A on the development of actively induced and passively transferred experimental allergic encephalomyelitis.

The immunosuppressive effects of cyclosporin A (CsA) were tested on actively induced and passively transferred experimental allergic encephalomyelitis (EAE). Actively induced EAE could be inhibited if CsA was administered per os at 25 mg/kg/day but not at 10 mg/kg/day. Passive transfer of clinical EAE occurred in all cell recipients including those fed CsA at either 25 or 50 mg/kg/day. Cyclosporin A could inhibit the development of transfer active cells in vitro and in vivo, however, inhibition of transfer active populations by CsA required the presence of CsA during the initial stage of cell response. If CsA was added to Con A-stimulated spleen cell cultures after a delay of 24 hr then these cells transferred clinical disease. Similarly, animals fed CsA concurrently with basic protein sensitization did not develop cell populations capable of transferring EAE. If CsA feeding commenced 2 or 4 days following sensitization all basic protein-sensitized animals still failed to develop EAE; however these latter groups of animals were a suitable source of cells capable of transferring some signs of clinical EAE.