Pharmacological comparison of active and passive experimental allergic encephalomyelitis in the rat.

Models of actively induced and passively transferred experimental allergic encephalomyelitis (EAE) have been compared in the rat. The time of disease onset, severity of clinical symptoms and percent incidence were compared and assessed for their suitability for evaluation of immunosuppressive agents. The passive EAE model had an earlier disease onset (6 +/- 0.1 days) and 100% of the cell recipients (n = 45) developed severe clinical symptoms, including paralysis of the tail and hind limbs. In contrast, the active EAE model had a mean disease onset day of 13 +/- 0.1 and only 53% of the induced rats (n = 85) developed EAE clinical symptoms which were variable. The average symptom score in both models was inhibited by dexamethasone (1 mg/kg/day p.o.; day 0 to 3), methotrexate (3 mg/kg i.p. single dose; day 1) and cyclosporin A (30 mg/kg/day p.o.; day 0 to 7). The above study indicates that the passive EAE model is more advantageous for pharmacologic evaluation of immunosuppressive agents.