Immune response after immunization with ovalbumin loaded polystyrene particles or adenoviral vectors. C57BL/6 mice were immunized twice by intradermal injection into the hind footpads with 50 ng soluble ovalbumin, ovalbumin-coated polystyrene particles of 24 nm (24p), 93 nm (93p) or 340 nm diameter (340p) carrying 50 ng ovalbumin, or 1010 vp ovalbumin-displaying adenovirus Ad.pIXova or UV-AdpIXova. Three weeks after boost-immunization, ovalbumin binding IgG1 (A) and IgG2c antibody levels were analyzed from 1:100 dilutions of plasma (B). For analysis of cellular immune responses, spleen cells were isolated and restimulated in vitro with ovalbumin-specific peptides, and IFNγ expression by CD8+ (C) and CD4+ T cells (D) was analyzed by flow cytometry. Statistically significant differences compared to naïve mice or mice immunized with soluble ovalbumin are indicated by * or #, respectively (P < 0.05, Student-Newman-Keuls method). The graphs show data of 8 mice per group that was acquired in two independent experiments, the bars indicate mean values.