Influence of particle size, antigen load, dose and additional adjuvant on the immune response from antigen loaded PLA microparticles

Abstract Polylactide (PLA) polymer particles entrapping tetanus toxoid (TT) were evaluated in terms of particle size, antigen load, dose and additional adjuvant for achieving high and sustained anti-TT antibody titer from single point intramuscular immunization. Admixture of polymer entrapped TT and alum improved the immune response in comparison to particle-based immunization. High and long lasting antibody titer was achieved upon immunization with 2–8 μm size particles. Microparticles within the size range 50–150 μm elicited very low serum antibody response. Immunization with very small particles (