Responses of primary CD4⁺ T cells to chemokine ligands in the context of altered T-bet levels. (A-C) Transmigration of CD4⁺ T cells in response to recombinant chemokine in the lower chamber of a transwell. (A-B) Chemotaxis of WT, T-bet^–/–, and T-bet^–/– × IFN-γ^–/– T cells to recombinant chemokines. (A) Chemotactic response to CXCL11 (I-TAC, 100 nM). □ indicates WT; ▪, T-bet ^–/–; ▦, T-bet^–/–/IFN-γ^–/–.(B) Chemotactic response to CCL4 (MIP-1β, 10 nM). □ indicates WT; ▪, T-bet^–/–; ▦, T-bet^–/–/IFN-γ^–/–. (C) Chemotaxis of retrovirally transduced T-bet (or empty vector control) into T-bet^–/– and T-bet^–/– × IFN-γ^–/– T cells to CXCR3 ligands, CXCL11 (100 nM), and CXCL10 (IP-10, 100 nM). □ indicates empty virus; ▪, T-bet^–/–; ▦, T-bet^–/–/IFN-γ^–/–. (D) Attachment of WT and T-bet^–/– T cells to unstimulated endothelial cells under shear flow in the absence or presence of CXCL10 (40 ng/mL) (mean ± SEM). □ indicates control; ▪, CXCL10. **P < .05.