Encephalitogenicity for rats of myelin basic protein without the aid of water-in-oil emulsions.

The induction of experimental allergic encephalomyelitis (EAE) with purified myelin basic protein (MBP) has, heretofore, required its incorporation in a water-in-oil emulsion or adsorption on particulate adjuvants. In the present work, the absorption of a saline solution of MBP from the peritoneal cavity into the mediastinal lymph nodes was increased by giving repeated inoculations or by pretreating rats with a peritoneal irritant. Under these conditions, the only adjuvant needed for production of EAE was aqueous pertussis vaccine which was injected separately a few hours or one day after the MBP. Pertussis vaccine was also necessary for production of EAE with intradermal injection of aqueous MBP. By injecting the aqueous MBP directly into pre-enlarged popliteal lymph nodes, it was possible to produce EAE without the pertussis vaccine. Thus, EAE can be induced in rats using MBP without the addition of Freund's adjuvant or pertussis vaccine.