An adjuvant formulation that selectively elicits the formation of antibodies of protective isotypes and of cell-mediated immunity.

Adjuvants are required to elicit protective immune responses with bacterial toxoids, inactivated viruses and subunit antigens produced by recombinant DNA technology. Some adjuvants, such as muramyl dipeptide (MDP) analog formulations, preferentially induce the formation of antibodies of isotypes that interact with complement and antibody-dependent effector cells, and do not elicit reaginic antibodies. Aluminum salts and mineral oil emulsions increase antibody formation but not cell-mediated immunity (CMI), whereas MDP formulations also elicit CMI. Adjuvants such as MDP and lipopolysaccharide (LPS) stimulate the production by accessory cells of IL-1 that increases the circulation of lymphocytes through draining lymph nodes and act as a growth factor for lymphocytes. Vehicles such as mineral oil emulsions, liposomes and Pluronic polymer formulations provide large surface areas on which antigens can be retained in a two-dimensional matrix, from which they can readily be transferred to antigen-presenting cells. The development of an adjuvant formulation able to elicit the formation of protective antibodies and CMI without unacceptable side effects is described.