title: In Vivo Analysis of the Potency of Silicone Oil Microdroplets as Immunological Adjuvants in Protein Formulations.
abstract: Subvisible particles in a therapeutic protein product may act as adjuvants to promote unwanted immune responses against the protein. Silicone oil is used as a lubricant in prefilled syringes, and microdroplets of silicone oil are often detected in protein formulations expelled from prefilled syringes. In order to test the adjuvant potency of silicone oil microdroplets, antibody responses in mice to subcutaneous injections of formulations of ovalbumin (OVA) that contained silicone oil microdroplets were measured. These responses were compared against responses to oil-free OVA formulations and to OVA formulations that contained microparticulate aluminum hydroxide ("alum"), the common vaccine adjuvant. When administered with high concentrations of silicone oil microdroplets, OVA formulations elicited strong anti-OVA IgG1 and IgG2a antibody responses. These responses were equivalent to those observed when alum microparticles were added to OVA formulations, suggesting that silicone oil can act as a potent adjuvant. However, when OVA formulations were prepared with lower levels of silicone oil that had been obtained directly from commercial siliconized syringes, the anti-OVA antibody response was not enhanced significantly compared with responses against OVA alone.
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309.
authors.forename: Carly Fleagle
authors.initials: CF
authors.lastname: Chisholm
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309.
authors.forename: Bao Han
authors.initials: BH
authors.lastname: Nguyen
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309.
authors.forename: Kaitlin R
authors.initials: KR
authors.lastname: Soucie
authors.affiliation: Department of Immunology & Microbiology, University of Colorado School of Medicine, Aurora, Colorado 80045.
authors.forename: Raul M
authors.initials: RM
authors.lastname: Torres
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045.
authors.forename: John F
authors.initials: JF
authors.lastname: Carpenter
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309. Electronic address: Theodore.randolph@colorado.edu.
authors.forename: Theodore W
authors.initials: TW
authors.lastname: Randolph
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000494:pharmacology*; D000536:Aluminum Hydroxide / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D000917:Antibody Formation / Q000187:drug effects*; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology*; D012827:Silicone Oils / Q000008:administration & dosage / Q000494:pharmacology*; D013594:Syringes
chemical_list: D000276:Adjuvants, Immunologic; D007074:Immunoglobulin G; D012827:Silicone Oils; D000536:Aluminum Hydroxide; D010047:Ovalbumin
keywords: adjuvant effect; immune response; immunology; particle size; prefilled syringes; protein aggregation; protein formulation; protein structure; silicone oil; subvisible particles