PHYSICAL STATE OF THE NEUROANTIGEN IN ADJUVANT EMULSIONS DETERMINES ENCEPHALITOGENIC STATUS IN THE BALB C MOUSE/

A novel form of adjuvant-neuroantigen formulation was established whic h was highly encephalitogenic in previously resistant BALB/c mice. The antigen formulation contained mouse whole spinal cord homogenate (MSC H), mycobacteria, and mineral oil, identically to the conventional pre paration, but emulsification was completed by sonication instead of ex trusion, Sonication of MSCH alone did not render a conventionally prep ared emulsion encephalitogenic. The novel adjuvant formulation showed reduced water-oil droplet size, and the neuroantigen was located on th e surface of the droplets as well as in the intermicellar space, while in the extruded formulation the material was buried in the droplet in terior, Mice inoculated with the sonicated emulsion showed strong brai n and spinal cord infiltration of lymphoid cells. The sonicated emulsi on was highly encephalitogenic in all six BALB/c substrains tested, Th e results suggest that availability of the neuroantigen is of critical importance for the development of clinical EAE in the BALB/c mouse.