Inhibition of EC function by anergic T cells is mediated by CD26. (Panels A-D) Responsive (▦) or anergic (□) human alloreactive T-cell lines were incubated with FITC-conjugated anti-TGFβ (panel A), anti–IL-10 (panel B), and anti-CD26 (panel C) mAbs. Cells were then analyzed by flow cytometry. The average median fluorescence intensity of CD26 expression by anergic T cells in 3 separate experiments was 162.68 ± 57.72 SD, while that of responsive T cells was 30.1 ± 3.8 SD. This difference was statistically significant (P < .02). Expression of CD26 by murine responsive and anergic T cells was also compared (clone B9; panel D). The average median fluorescence intensity of CD26 expression by murine anergic T cells in 3 separate experiments was 5.6 ± 0.8, while that of responsive T cells was 1.5 ± 2.1 SD. This difference was statistically significant (P < .05). (Panels E-H) Responsive (105/well; panels E,G) and anergic (5 × 104/well; panels F,H) T-cell lines were treated for 30 minutes at 4°C with an anti-CD26 antibody or with an isotype-matched control mAb and washed prior to being added to TNF-α–treated EC monolayers grown on 12-mm–diameter transwells (5 × 104/well). As a control, EC monolayers were incubated in medium alone. T cells were subsequently removed and fresh 7P.61 T cells (7 × 105/well; panels E-F) or granulocytes (106/well; panels G-H) were seeded onto the EC monolayers. The results are expressed as percentage of migrated T cells at the given time points and are reported as the average of 3 experiments of identical design. The bars show the SD. * indicates statistically significant (at least P < .03, panel F; at least P < .03, panel H) versus control cultures (EC monolayers cultured with anergic T cells).
