RESUMO
BACKGROUND: Experimental autoimmune encephalomyelitis (EAE) induced by the myelin oligodendrocyte glycoprotein (MOG) peptide 35-55, is a widely used multiple sclerosis (MS) model. Unlike the spontaneous occurrence of MS, in EAE, external immunization with the MOG peptide (200-300 µg/mouse), emulsified in adjuvant enriched with Mycobacterium Tuberculosis (MT) H37Ra (100-500 µg mouse), and pertussis toxin (PTx, 200-500 ng/mouse) injections, are applied, which heavily boosts the immune system. NEW METHOD: A detailed and systematic titration of the MOG 35-55 EAE induction protocol in C57BL/6 mice reveals the minimal doses of the MOG 35-55 peptide, MT H37Ra, and PTx, required for disease manifestation. RESULTS: The amounts of MOG 35-55 peptide, MT H37Ra, and PTx can be drastically reduced from the standard protocol, to level of 5 µg MOG, 25 µg MT H37Ra, and 50 ng PTx, without affecting the clinical manifestations. The titrated protocols induced a high disease incidence and a consistent robust disease course, with full histopathological characteristics of the MOG model, inflammation, demyelination and axonal damage. COMPARISON WITH EXISTING METHODS: Similar disease incidences, day of symptoms appearance, maximal clinical score, and histopathology were obtained for the standard and the titrated protocols. CONCLUSIONS: Reducing the reagent dosages used for EAE induction, without attenuating the disease, can give a truer and less artificial perspective of MS. We propose an improved protocol for this extensively used model, with high disease incidence, a consistent robust course, and characteristic histological manifestations, which may be more sensitive for testing therapeutic modalities, cost-effective, and less distressing to the animals.