The production of EAE in the fully susceptible BSVS mouse genotype has been found to be dependent on the ratio of proteolipid antigen and adjuvant mycobacterial concentration as used in the emulsion, of the Freund type. Disturbance of this ratio, by manipulation of either component, by diminution or increase, results in a decrease in the frequency by which EAE is produced.
Simultaneous reduction of antigen and mycobacteria, so that the ratio remains unchanged, retains the full EAE-producing power of the emulsion. The limit of this has not been ascertained.
Emulsifying agents have been found to restrict further the permissible limits of the antigen-mycobacterial ratio for full EAE production. Such effects of the emulsifier have been found to vary with the qualitative nature of the emulsifier. Aquaphor has been found to be less restrictive than falba.
These phenomena, systematically analyzed here for the mouse, may have an application for other antigen-adjuvant systems and for other hosts.