Influence of particle size and antigen binding on effectiveness of aluminum salt adjuvants in a model lysozyme vaccine

It has been suggested that agglomeration of aluminum salt adjuvant particles during freezing and drying can cause loss of immunogenicity of vaccines formulated with such adjuvants. In this study, we tested this hypothesis and examined the immune response in a murine model to various liquid, freeze-thawed, and lyophilized vaccine formulations, using lysozyme as a model antigen. The various processing techniques and excipient levels resulted in a wide range of particle size distributions (PSDs) and antigen-adjuvant binding levels. Anti-lysozyme titers were independent of the PSD for vaccines adjuvanted with either aluminum hydroxide or aluminum phosphate and also were unaffected by the level of antigen binding to the adjuvant.