FIG. 6.

Functional role of B7 on SBR-specific CD4⁺-T-cell proliferation and cytokine production. CD4⁺ T cells from the spleens of immunized mice were cultured in the presence of naïve feeder cells and SBR for 24 h. Proliferation of SBR-specific CD4⁺ T cells was determined by a liquid scintillation counter following the addition of 0.5 μCi/well of [³H]thymidine for the last 18 to 24 h of culture. The results are expressed as the Δcpm (experimental cpm − nonstimulated cpm) (A). Cytokine production (IL-4, IL-5, and IFN-γ) in culture supernatants of SBR-stimulated cultures was assessed at 24 h (B, C, and D, respectively). Results represent the arithmetic mean ± SEM of six mice per group. ** and *** indicate significant differences between the wt and the other groups of mice at P < 0.01 and P < 0.001, respectively.