title: Soluble CD26/dipeptidyl peptidase IV induces T cell proliferation through CD86 up-regulation on APCs.
abstract: CD26 is a T cell costimulatory molecule with dipeptidyl peptidase IV enzyme activity in its extracellular region. We have previously reported that the addition of soluble CD26 (sCD26) resulted in enhanced proliferation of peripheral blood T lymphocytes induced by the recall Ag, tetanus toxoid (TT). However, the mechanism involved in this immune enhancement has not yet been elucidated. In this paper, we demonstrate that the enhancing effect of sCD26 on TT-induced T cell proliferation occurred in the early stages of immune response. The cells directly affected by exogenously added sCD26 are the CD14-positive monocytes in the peripheral blood. Mannose-6 phosphate interfered with the uptake of sCD26 into monocytes, suggesting that mannose-6 phosphate/insulin-like growth factor II receptor plays a role in the transportation of sCD26 into monocytes. When sCD26 was added after Ag presentation had taken place, enhancement in TT-induced T cell proliferation was not observed. In addition, enhancement of TT-mediated T cell proliferation by sCD26 does not result from trimming of the MHC-bound peptide on the surface of monocytes. Importantly, we also showed that exogenously added sCD26 up-regulated the expression of the costimulatory molecule CD86 on monocytes through its dipeptidyl peptidase IV activity, and that this increased expression of CD86 was observed at both protein and mRNA level. Therefore, our findings suggest that sCD26 enhances T cell immune response to recall Ag via its direct effect on APCs.
authors.affiliation: Division of Clinical Immunology, Advanced Clinical Research Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ohnuma
authors.forename: Y
authors.initials: Y
authors.lastname: Munakata
authors.forename: T
authors.initials: T
authors.lastname: Ishii
authors.forename: S
authors.initials: S
authors.lastname: Iwata
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: O
authors.initials: O
authors.lastname: Hosono
authors.forename: H
authors.initials: H
authors.lastname: Kawasaki
authors.forename: N H
authors.initials: NH
authors.lastname: Dang
authors.forename: C
authors.initials: C
authors.lastname: Morimoto
mesh_terms: D000069594:Abatacept; D000328:Adult; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000938:Antigen-Presenting Cells / Q000276:immunology*; D000941:Antigens / Q000276:immunology; D015703:Antigens, CD / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D000943:Antigens, Differentiation / Q000494:pharmacology; D051940:B7-2 Antigen; D060908:CTLA-4 Antigen; D002478:Cells, Cultured; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism / Q000494:pharmacology*; D004705:Endocytosis; D006801:Humans; D018796:Immunoconjugates; D007156:Immunologic Memory; D007700:Kinetics; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D009000:Monocytes / Q000187:drug effects / Q000276:immunology*; D012333:RNA, Messenger / Q000096:biosynthesis; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D013745:Tetanus Toxoid / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D000911:Antibodies, Monoclonal; D000941:Antigens; D015703:Antigens, CD; D000943:Antigens, Differentiation; D051940:B7-2 Antigen; C497964:CD86 protein, human; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D018796:Immunoconjugates; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D017527:Receptor, IGF Type 2; D013745:Tetanus Toxoid; D000069594:Abatacept; D018819:Dipeptidyl Peptidase 4