Figure 3.

Flow cytometry analysis of Adjuvant System 37 (AS37), which comprises aluminum hydroxide (AH) and an adsorbed TLR7 agonist. The histogram shows how the AH alone (red trace), which displays a negative fluorescence intensity, shows an increase in fluorescent signal after formulation with a high dose (HD) of TLR7a (blue trace): these data represent a direct confirmation of TLR7a adsorption onto AH. AS37 HD has a unique and monodispersed peak, meaning that almost all AH particles deliver a similar amount of agonist. The samples in green and orange instead represent the AS37 HDs that were, respectively, diluted 1:2 and 1:3 with AH alone to reach a lower TLR7 agonist dose whilst keeping the AH amount constant. As a consequence of sample dilution, the fluorescence intensity decreased relative to the TLR7a dose, always maintaining a monodispersed TLR7a distribution over AH particles. X-axis indicates fluorescence intensity and the Y-axis the percentage of the maximum number of events. Adapted from Reference [127].