Cytokine profiles of splenocytes obtained from immunized mice. Mice were primed with Ap97, ApxN, or P97C vaccines. Splenocytes were isolated from each mouse and then re-stimulated with Ap97, ApxN, or P97C dissolved in PBS. At the end of re-stimulation, cell culture supernatants were analyzed for IFN-γ (A) and IL-4 (B). Data represent the mean ± SD (n = 4). *P < 0.05 and **P < 0.01, significantly different from the corresponding PBS-treated controls (paired t-test).