title: Association of CD26 with CD45RA outside lipid rafts attenuates cord blood T-cell activation.
abstract: CD26 is a T-cell activation antigen that contains dipeptidyl peptidase IV activity and binds adenosine deaminase. Recent work showed that specialized membrane microdomains, also known as lipid rafts, play a key role in T-cell signaling. In this study, we investigate the role of CD26 in cord blood T-cell activation and signal transduction. We demonstrated that different expression levels of CD26 were observed between cord blood T cells (CBTCs) and peripheral blood T cells (PBTCs) and that CD26(+)CD45RA(+) CBTCs were different compared with CD26(+)CD45RA(+) PBTCs. Moreover, the comitogenic effect of CD26 was not as pronounced in CBTCs as in PBTCs. We also showed that CD26 cross-linking induced less phosphorylation of T-cell receptor-signaling molecules, lymphoid T-cell protein tyrosine kinase (Lck), zeta-associated protein 70 (ZAP-70), T-cell receptor zeta (TCRzeta), and linker for activator of T cells (LAT) in CBTCs than in PBTCs. Furthermore, CD26 molecules associated with CD45RA molecules outside lipid rafts in CBTCs. Our results suggest that strong physical linkage of CD26 with CD45RA outside lipid rafts may be responsible for the attenuation of T-cell activation signaling through CD26, which may be responsible for immature immune response and the low incidence of severe graft-versus-host disease in cord blood transplantation.
authors.affiliation: Division of Clinical Immunology, Advanced Clinical Research Center, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Kei
authors.initials: K
authors.lastname: Ohnuma
authors.forename: Masahiko
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Kouichi
authors.initials: K
authors.lastname: Iino
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iwata
authors.forename: Nam H
authors.initials: NH
authors.lastname: Dang
authors.forename: Chikao
authors.initials: C
authors.lastname: Morimoto
mesh_terms: D017252:CD3 Complex / Q000378:metabolism; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D017493:Leukocyte Common Antigens / Q000378:metabolism*; D008213:Lymphocyte Activation; D021962:Membrane Microdomains / Q000276:immunology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D017252:CD3 Complex; D017493:Leukocyte Common Antigens; D018819:Dipeptidyl Peptidase 4