The Mucosal Adjuvant Potential of Cross-Linked Dextran Microspheres as Dry Powder

Objective(s) The immunoadjuvant potential of cross-linked dextran microspheres (CDM) as absorption enhancer and Quillaja saponins (QS) as immunomodulator adjuvant was evaluated. Materials and Methods CDM loaded or tetanus-mixed toxoid (TT) or Quillaja saponin (QS) were nasally administered to rabbits in dry powder form, three times in 2 weeks interval and serum IgG and nasal lavage sIgA titers were determined by ELISA. Results The highest serum IgG titer was induced by parenteral immunization through alum adsorbed TT (P< 0.001). Among nasally immunized groups, the highest serum IgG titer was induced by (TT+QS)CDM (P< 0.01). Mixing of CDM with TT+QS powders (CDM+TT+QS), could not induce the high serum IgG titers as (TT+QS)CDM (P< 0.01). CDM loaded with TT+QS induced higher IgG titers than CDM loaded with TT alone (P< 0.01). No significant difference was observed in nasal lavage sIgA titers of various groups.   Conclusion CDM microspheres loaded with TT+QS significantly increased serum anti-TT IgG titers, but mixing of CDM with TT+QS powder could not increase IgG titers. Both QS and CDM adjuvant could not significantly increase the lavage anti-TT IgA titers.