Neuropathological comparative studies on experimental allergic neuritis (EAN) induced in rabbits by P2 protein-ganglioside complexes.

The light microscopical examinations were performed on the peripheral nerve (PN) lesions in rabbits induced by bovine peripheral nerve (BPN) myelin and by its components. Morphology of the PN lesions induced by P2 protein-ganglioside complex were equivalent to those induced by PN myelin (original EAN); and some of them were more remarkable in severity than the original EAN. The lesions were composed of myelin destruction, numerous macrophages containing myelin debris, completely demyelinated axons and remyelinating fibers. P2-I, acid treated P2-I and P2-II proteins induced PN lesions. Histologically they were moderate to minimal in severity in that order. However, when each protein was injected as the complex with ganglioside, PN lesions obviously became severer, respectively. These findings indicate the possibility that the P2-ganglioside complex may be involved in the chemical principle of EAN, and also the findings strongly support the theory proposed by Nagai et al. that gangliosides may play an essential role in rabbit EAN to give P2 protein a special conformation necessary for antigenic activity.