(A and B) HY-specific H2-A^b–restricted WT and P110δ^D910A CD4⁺ T cells (5 × 10⁵/well) were exposed to CXCL10 (300 ng/ml; filled symbols, A and D), CXCL12 (50 ng/ml; filled symbols, B and E), or CCL5 (100 ng/ml; filled symbols, C and F) through 5-μm-pore Transwells. In the experiments analyzing migratory responses to CXCL12, T cells were stimulated with plastic-bound anti-CD3 (1 μg/ml) and anti-CD28 (5 μg/ml) for 72 hours to induce CXCR4 expression. Spontaneous migration in chemotaxis medium (RPMI 0.5% FCS) alone was also measured (open symbols). The number of migrated T cells was monitored at the indicated time points. Results are expressed as the percentage of input T lymphocytes that had migrated through the filters at any given time point and represent the mean of at least 3 independent experiments ± SEM. *P < 0.05 at all time points except 2 hours (B, C, and E) and 24 hours. (G–J) C57BL/6 female mice received an i.p. injection of CXCL10 (1,200 ng). One hour later, PKH26-labeled HY-specific H2-A^b–restricted WT and P110δ^D910A T cells (5 × 10⁵/well) T cells were injected i.v. After 6 hours, localization of PKH26-labeled T cells in the peritoneal cavity was assessed by flow cytometry. The panels (representative of 1 experiment) show the number of PKH26-labeled T cells in the CD4-gated T cell population. The mean T cell numbers ± SEM observed in samples from at least 3 animals are summarized in K. *P < 0.02.