Aim: To combine the dimethyldioctadecyl ammonium/monomycoloyl glycerol (DDA/MMG) liposomal vaccine adjuvant with the Toll-like receptor (TLR) ligands poly(I:C) (TLR3), flagellin (TLR5) or CpG oligodeoxynucleotide 1826 (TLR9) and investigate their physicochemical properties as well as their CD4(+) T-cell-inducing capacity.
Materials & methods: Formulations were investigated by dynamic light scattering and differential scanning calorimetry. Their CD4(+) T-cell induction with a tuberculosis antigen was analyzed by multiplex cytokine analysis, ELISA and intracellular cytokine staining.
Results: DDA/MMG/CpG was the best combination for obtaining increased CD4(+) T-cell responses. However, coformulating CpG and DDA/MMG liposomes led to instability and the formulation was therefore optimized systematically using a design of experiment.
Conclusion: The nanoparticulate DDA/MMG/CpG adjuvant can be stabilized and synergistically enhances CD4(+) T-cell responses compared with DDA/MMG liposomes.
Keywords: CD4+ T cells; CpG; adjuvant; cationic liposome; pattern-recognition receptors.