Fig. 1.

Effect of plasmid-derived IL-15 and IL-21 on the 47-LDA vaccine-induced cellular and humoral responses in A/J mice. Mice (n = 4) were immunized with the 47-LDA vaccine in the absence, presence or combination of IL-15 and IL-21 genes. Three weeks after immunization, the animals were sacrificed and spleens and blood were collected. Splenocytes were isolated and cultured overnight with the 47-LDA-transfected DCs at the 20:1 ratio. a The expression of IFN-γ and TNF-α in CD4⁺ T cells was analyzed by intracellular staining, and presented after subtracting the numbers of CD4⁺ cells expressing IFN-γ or TNF-α in cultures of splenocytes from mice immunized with the sham vector. b The titers and isotypes of GD2 cross-reactive antibodies in sera of the same group of immunized mice were determined by ELISA. The titers are shown as the highest serum dilutions with significantly different OD as compared with sera from sham vector-immunized mice using paired Student’s t test (P < 0.05). All results are presented as the means ± SD (error bars) of at least three independent experiments. * P < 0.01; ** P < 0.001; *** P < 0.0001