Figure 1.

S2-16:IFA-induced protection was associated with expansion of S2-16-reactive T cells producing low levels of IFN-γ and IL-2 but high levels of IL-10. Lewis rats were administered S2-16:IFA or control PBS:IFA 14 days before challenge by immunization with S2-16:CFA. Splenic lymphocytes were collected 21 days after challenge. A: Proliferative responses of splenocytes with different concentrations of S2-16 peptide. Proliferation was measured by ³H-thymidine incorporation. Results of proliferative assay were expressed as stimulation index (SI) (mean test counts per minute/mean of medium control counts per minute). B: IL-2, IL-10, and IFN-γ production by splenocytes cultured with S2-16. Supernatants were collected at 24 hours for IL-2, 48 hours for IFN-γ, and 72 hours for IL-10, and cytokine levels were measured by cytokine-specific ELISA. Error bars represent SEMs, and Student’s t-test was used to determine the significant differences between PBS:IFA-pretreated group and S2-16:IFA-pretreated group (*P ≤ 0.05, **P ≤ 0.005). Cytokine levels of cells cultured with medium alone were <20% of cytokine response to S2-16, and are not shown in figure.