Pretreatment with antigen or adjuvant, and the preventability of allergic encephalomyelitis induced by basic protein with synthetic muramyl dipeptide in comparison with Freund's complete adjuvant.
Protection against experimental allergic encephalomyelitis (EAE) was examined by prior injection of following materials with Freund's incomplete adjuvant (FIA), Mycobacterium tuberculosis (Tbc), synthetic muramyl dipeptide (Mdp), polyinosinate-polycytidylate (poly IC), or myelin basic protein (BP). 26 days later, guinea pigs received encephalitogenic challenge in the form of 20 micrograms BP + 20 micrograms Tbc in FIA (BP + Tbc) or 20 micrograms BP + 10 micrograms Mdp in FIA (BP + Mdp). (1) Either pretreatment with Mdp, poly IC or FIA alone showed no protecting effects. (2) Tbc/FIA was not effective on challenge with BP + Mdp, but effective on challenge with BP + Tbc, and produced passive hemagglutinating (PH) antibodies of moderate titer and and complement fixing (CF) antibodies of higher titer. (3) BP/FIA was effective on both BP + Tbc and BP + Mdp challenges, and produced PH antibodies of higher titer than that of CF antibodies. (4) Clinicopathological survey revealed that the challenge with BP + Mdp was blocked perfectly by prior injection with BP/FIA whereas the challenge with BP + Tbc was incompletely blocked by either Tbc/FIA or BP/FIA pretreatment. (5) The finding was verified also by cerebrospinal fluid cell count at the termination of clinical observation. As compared with FCA, Mdp adjuvant itself has no antigenic component, which seems to explain the results in this study.