P2 protein-induced experimental allergic neuritis. An ultrastructural study

Area of Science:

• Neuroimmunology
• Pathology

Background:

• Experimental allergic neuritis (EAN) is an autoimmune model of demyelinating polyneuropathy.
• P2 protein and peripheral nervous system (PNS) myelin are known encephalitogenic antigens.

Purpose of the Study:

• To investigate the demyelinative lesions induced by P2 protein in Lewis rats.
• To compare P2-induced EAN with PNS myelin-induced EAN and experimental allergic encephalomyelitis (EAE).

Main Methods:

• Induction of EAN in Lewis rats using purified bovine P2 protein and PNS myelin.
• Light and electron microscopic examination of neural tissues.

Main Results:

• P2-induced EAN exhibited demyelinative lesions in spinal ganglia and root nerves, affecting both small and large myelinated fibers.
• Lesions included lymphocytic infiltration and myelin sheath dissolution with phagocytic cell invasion.
• P2-induced EAN showed milder disease, more frequent myelin dissolution, and intramyelinic edema compared to PNS myelin-induced EAN.
• Significant demyelination in P2-induced EAN contrasted with minimal myelin changes in EAE induced by myelin basic protein.

Conclusions:

• P2 protein induces significant demyelination in the spinal cord and peripheral nerves, affecting various fiber sizes.
• The pattern of demyelination in P2-induced EAN differs from EAE, suggesting distinct pathogenic mechanisms.
• P2 protein is a potent inducer of demyelinating lesions in the nervous system.