Straight Chain Hydrocarbons as Substitutes for the Oil in Freund's Adjuvants in the Production of Experimental “Allergic” Encephalomyelitis in the Guinea Pig

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Abstract
Summary: Straight chain hydrocarbons with 15 to 20 carbon atoms (pentadecane through eicosane) substitute quite effectively for the standard mineral oils in Freund's adjuvants as judged by the production of experimental “allergic” encephalomyelitis in the guinea pig. The longer hydrocarbon (tetracosane) is solid at body temperature and is completely ineffective. These observations suggest that the oil acts physically to promote diffusion of the encephalitogenic emulsion. Since the shorter hydrocarbons with 6 to 13 carbon atoms (hexane through tridecane) are generally much better solvents but are only slightly effective as adjuvant, and since oil from which the tubercle bacilli have been removed is completely ineffective, it is further concluded that the oil does not extract significant amounts of active materials from the bacilli.