Fig. 1.

TLR4 signaling enhances CD4⁺ T-cell activation. (A) Sorted naïve CD4⁺ T cells were differentiated under various Th conditions for 4 d followed by intracellular cytokine staining. (B) Naïve CD4⁺ T cells from WT or Tlr4^−/− mice were treated 3 d with media, 1 μg/mL αCD28, or αCD28 + αCD3 in the absence or presence of LPS. Data are presented as mean + SD for triplicate determinations; *P < 0.05; Student's t test. (C) WT or Tlr4^−/− CD4⁺ T cells were left untreated for 3 d in the absence or presence of LPS before analysis by 7-AAD and Annexin-V staining. Data are representative of three independent experiments.