EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS INDUCED BY MOUSE BRAIN TISSUE

Experimental allergic encephalomyelitis was regularly produced by injection of normal mouse brain tissue, or as controls with rabbit spinal cord tissue, emulsified with an adjuvant containing heat-killed BCG and liquid paraffin in guinea pigs, monkeys and albino rats; however, it was much less frequently induced in rabbits and white mice.In the guinea pigs, the typical findings of the disease was a paralysis of the hind legs and death from ascending paralysis. In a few animals, however, following paralysis of one of the limbs, a gradual recovery was observed. In all cases, too, marked reduction in body weight was noticed. Comparing with the results obtained when the rabbit nerve tissue was employed, it was found that in these animals, the use of rabbit cord tissue and the inoculation by intracutaneous route produced the most reliable results.In the albino rats, with the mouse brain emulsion given intracutaneously, 17 out of 20 developed paralysis of both hind legs with an incubation period of 13--22 days.When the inoculation was made subcutaneously no symptoms of the disease was found. In the monkeys, among a group of 5 animals given intracutaneously 2 doses of 0.1 ml seven days apart, 2 came down with a non-fatal form of the disease. One showed paralysis of both hind legs, while the other only paresis, loss of appetite and loss of body weight. Among the group of 5 animals receiving 2 doses of 1 ml at 7 days' interval subcutaneously, 2 also came down with the disease. One recovered after the exhibition of paralysis of the extremities and the other succumbed with ascending paralysis. Post mortem findings revealed hemorrhagic foci, perivascular demyelination and perivascular cellular infiltration in the brain. After having recovered or remained healthy after the first series of injections, 8 monkeys were reinoculated with the same materials by the intramuscular route. Two or 3 doses of 1 ml -each were given to each animal. As a result, 7 developed encephalomyelitis and 6 died of paralysis with hemorrhagic foci and perivascular demyelination in the brain. The only monkey remained alive showed tremor of fore limbs as a sequela.It was noted that the clinical findings of the disease in monkeys were much more complex than those found in the guinea pigs. Besides paralysis of the limbs, ptosis,dilatation or contraction of the pupils, defective vision or even blindness, convulsion,tremor and other nervous symptoms were all encountered in the monkeys. Histologically, perivascular cellular infiltration in meninges and subependyma were the prominent changes in the guinea pigs whereas demyelination in the white matter was the principle lesion in the monkeys.