In 1942 it was shown by Freund1 and afterward confirmed by Friedewald that the immune response of animals may be prolonged and often elevated by injecting antigens in the aqueous phase of saline in liquid petrolatum emulsions.1 Applying the emulsion technic Mudd and his associates of the University of Pennsylvania subsequently attempted to improve the immunologic response to dysentery vaccines.2 Falba, a stabilizing agent derived from lanolin, was mixed by an electric stirrer with a saline suspension of alcohol killed Shigella paradysenteriae bacilli until a smooth paste was obtained. Liquid petrolatum was then added and stirred until the emulsion was well diffused. The proportion of the constituents, antigen in saline: falba: liquid petrolatum was 1:1:4 respectively.
Thirty-five inbred white Swiss mice were given a single subcutaneous injection of 20 micrograms of S. paradysenteriae cells in 0.15 cc. of saline solution. A similar group was injected with 20
FREUND'S EMULSIFIED VACCINES. JAMA. 1946;130(12):789-790. doi:10.1001/jama.1946.02870120035011