Fig. 5.

T-cell proliferative responses of SBR (A) or Salmonella (B)-specific CD4⁺ T cells isolated 2 wks after the last immunization of mice. Immunization procedure is as described in legend to Figure 1. CD4⁺ T cells (2 × 10⁶/ ml) were isolated from the spleens and were co-cultured with irradiated, T cell-depleted splenic feeder cells (5 × 10⁶/ml) in the presence or absence of SBR (2 µg/ml) or of killed Salmonella (10⁷ equivalent cfu/ml). Proliferation of antigen-specific CD4⁺ T cells was determined following the addition of 0.5 microCi/well of [³H]TdR for the last 18 h of a 96-h culture. The results are expressed as the mean ×/÷ SD. Values were significantly different from those of wt mice at P < 0.05 (*) and P < 0.005 (**).