Physicochemical properties of particulate vaccine adjuvants: their pivotal role in modulating immune responses

Abstract

Vaccine adjuvants enhance immunogenic responses of antigens and increase potency of vaccines. Physicochemical properties of particulate vaccine adjuvants namely, particle size, surface charge, hydrophobicity, shape and composition play an important role to determine their activity and potency. Various studies have been done using different types of particulate vaccine adjuvants to correlate their physicochemical properties with immune responses. Generally, change in particle size does not show any trend in modulation of immunogenicity, however, it directly influences on cellular uptake of particles, leading to alteration of cytokine profile and induction of Th1 and/or Th2 responses. Usually, positively charged adjuvant particles undergo higher cellular uptake than negatively charged particles and hydrophobic particles undergo cellular uptake more efficiently than hydrophilic particles. Furthermore, shape and composition of adjuvant particles also influence on immune responses. This review gives an insight into the impact of particle size, surface charge, hydrophobicity, shape and composition of particulate vaccine adjuvants in modulating immune responses. © 2018, The Korean Society of Pharmaceutical Sciences and Technology.