CD26 (Dipeptidyl peptidase IV) on human T lymphocytes does not mediate adhesion of these cells to endothelial cells or fibroblasts

We have examined the role of CD26 (dipeptidyl peptidase IV) in the adhesion of resting and activated T lymphocytes to endothelial cells and fibroblasts. For this purpose, ave ran a short-time adhesion assay under different strategies: Adhesion of T lymphocytes was determined in the presence of different anti-CD26 monoclonal antibodies, or in the presence of synthetic inhibitors of the enzymatic function of CD26. In addition, the expression of CD26 on T lymphocytes, which were adherent to endothelial cells or fibroblasts, was performed by flow cytometric analysis. We found that the anti-CD26 monoclonal antibodies tested here were not able to inhibit T cell adhesion to monolayers of endothelial cells or fibroblasts. Secondly, synthetic inhibitors of the enzymatic function of CD26 had no effect on the adhesion of T lymphocytes to endothelial cells or fibroblasts. Furthermore, CD26-positive T cells were not accumulated in the adherent population. These results suggest that CD26 on T lymphocytes plays no role in T cell adhesion to endothelial cells or fibroblasts.