Cross-linking of PSGL-1 induces activated mouse T-cell death. Mouse splenocytes of B6 mice stimulated with ConA (A-B) and those of AND TCR transgenic mice stimulated with specific antigen, PCC (C), were used. At the indicated time, activated mouse T cells were incubated with rabbit antihamster antibody plus TAB4 or control antibodies. After 6 hours, the cell death was assayed by flow cytometry with Annexin-V FITC and propidium iodide staining. Error bars in panels B and C indicate standard deviation. (D) PSGL-1 expression on T cells at different activation stages was detected by staining with TAB4 (coarse line) or hamster Ig (fine line), followed by antihamster FITC and analyzed by flow cytometry. The data represent at least 3 independent experiments and were analyzed by ANOVA test with Bonferroni correction for multiple comparisons. *Difference of cell death between TAB4-treated and negative control antibody–treated groups, P < 0.01. ∧ Significant increase of TAB4-induced cell death with time, P < .01