Effect of PLGA Microsphere Size on Regulation of Immune Response for HPV L1 Capsomere-based Candidate Vaccine

Two-sized poly(lactic-co-glycolic acid)(PLGA) microspheres prepared by membrane emulsification technique were used as vaccine delivery and adjuvant system.The effect of particle size on enhancing HPV LI specific immune responses was investigated.The results showed mat HPV LI pentamers encapsulated in large-sized PLGA(1.38 um) microspheres could elicit significantly higher level of IgG binding antibodies(87771 ±24983.0) and neutralizing antibodies(30720115863.7) man the counterparts with 0.43 μm(38400114021.7) and(248013892.6)(P0.05 and F0.01).The similar trend was also found in cytokine secretion levels,and higher levels of IL-6(4.7 times of the cytokines for small-sized microspheres) and IL-4(l.S times of the cytokines for small-sized microspheres) were observed in mice immunized with large-sized PLGA microspheres(1.38 μm) encapsulating HPV L1 pentamers.While small-sized PLGA microspheres(0.43 μm) encapsulating HPV L1 pentamers elicited significantly higher IFN-7 secretion levels(2.1 times of the cytokine for the large-sized microspheres) than large-sized PLGA microspheres(1.38 um).Small-sized PLGA microspheres can enhance antigen specific cellular immune responses,which is suitable for therapeutic vaccine,while large-sized PLGA microspheres can elicit higher level of humoral immune responses,which is favorable for prophylactic HPV vaccine.