The neuritogenicity and encephalitogenicity of P2 in the rat, guinea-pig and rabbit

In inbred Lewis rats, P2 basic protein from bovine peripheral nervous system (PNS) myelin produced experimental allergic neuritis (EAN) without involvement of the brain or spinal cord. In guinea-pigs, bovine P2 did not produce EAN but large doses produced mild experimental allergic encephalomyelitis (EAE). In rabbits, bovine P2 produced both mild EAE and EAN. Human P2 produced severe EAN in the Lewis rat, but only mild EAN with quite marked EAE in the guinea-pig. Material cross-reacting with bovine P on immunodiffusion was identified in the extracts from the nerves of all three species but only in the spinal cord of the guinea-pig and rabbit, not in the rat spinal cord. The species differences in response to immunisation with P2 cannot be simply explained by the presence or absence of P2 in their PNS or CNS, but may reflect differences in the immune response.