Enzymatic activity of CD26 (dipeptidylpeptidase IV) is not required for its signalling function in T cells.
CD26 is a proteolytic enzyme (dipeptidylpeptidase IV) expressed on the T cell surface that defines an alternative activation signal for human T lymphocytes. Crosslinking of CD26 via monoclonal antibodies triggers proliferation and cytotoxicity in preactivated T cells. In this study, we used highly specific competitive and irreversible inhibitors of dipeptidylpeptidase IV to study the role of the enzymatic activity in activation of CD26-transfected T cells as well as of CD26-expressing normal human T cell clones. These inhibitors at concentrations that blocked up to 95% of the enzymatic activity, did not specifically inhibit T cell activation neither via TCR/CD3 nor via CD26 itself. This demonstrates that the enzymatic activity of CD26 is not required for its T cell activating properties.
Hegen
M
M
First Department of Medicine, University of Mainz, Germany.
Mittrücker
H W
HW
Hug
R
R
Demuth
H U
HU
Neubert
K
K
Barth
A
A
Fleischer
B
B
D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000502:physiology*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D014407:Tumor Cells, Cultured
D000945:Antigens, Differentiation, T-Lymphocyte; D007376:Interleukin-2; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4