Suppression of experimental allergic encephalomyelitis by retinoic acid.

Administration of retinoic acid (RA) prevented the development of experimental allergic encephalomyelitis (EAE) in Lewis rats. RA suspended in corn oil was given for 3 days before the expected onset of the disease to rats immunized with myelin and to controls. The drug suppressed the neurological symptoms as well as the perivascular infiltrates observed in vehicle-treated animals. The results indicate that under these experimental conditions, RA has immunosuppressive activity by interfering with the efferent phase of the immune response.