To assess the degree of DC maturation resulting from exposure to different adjuvants, cells were exposed to varying concentrations of aluminium hydroxide gel, Alhydrogel (Sigma Aldrich, Missouri, USA), E 8 Pam 2 Cys or lipopolysaccharide (5 mg/ml) as a positive control (LPS; Sigma Aldrich, Milwaukee, USA). In some experiments, cells were incubated with VLPs alone (5 mg/ml) or in the presence of E 8 Pam 2 Cys (0.032 mg/ml). After 16 hours, cells were harvested, washed and analysed for expression of surface Class II MHC antigen.