Characterization of a nontoxic monophosphoryl lipid A.

Gram-negative bacterial endotoxins constitute some of the strongest immunologic adjuvants known. Precluding their use as adjuvants in humans has been the exquisite toxicity of these compounds in extraordinarily small amounts. With the acquisition of precise knowledge of the structure of the active moiety, detoxifying procedures have been developed. These have resulted in the isolation of a monophosphoryl lipid A with a much reduced toxicity that retains the capacity to act as an adjuvant in young mice as well as in immunodeficient aging mice.