The adjuvant activity of nonionic block polymer surfactants. II. Antibody formation and inflammation related to the structure of triblock and octablock copolymers.

We tested the ability of 17 surface-active agents to enhance antibody formation and inflammation. The surfactants were all block copolymers of hydrophilic polyoxyethylene (POE) and hydrophobic polyoxypropylene (POP), which differed in m.w. and mode of linkage of POP to POE. Mice were injected in each rear footpad with 1.25 mg of each surfactant with 25 micrograms of bovine serum albumin in an oil-in-water emulsion. Each agent produced a distinct pattern of immune response and inflammation. Preparations that are large and insoluble with the POE chains flanking the POP chains were very effective adjuvants for increasing antibody formation. They also activated complement and induced the release of chemotactic factors from serum. Increasing the percent of POE decreased adjuvant activity and inflammation. Decreasing the m.w. of the molecules while maintaining the proportions of POP and POE decreased the adjuvant activity and increased inflammation. Preparations synthesized in the reverse order, with the POP flanking POE, tended to induce granulomas instead of antibody. These data demonstrate that block copolymer surfactants have a spectrum of biologic activities that depend on the size and arrangement of their constituent parts. We suggest that much of the activity of these agents derives from their ability to form adsorptive surfaces similar to those of a mycobacterial glycolipid, quartz, and monosodium urate.