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Binding of the T Cell Activation Monoclonal Antibody Ta1 to Dipeptidyl Peptidase IV
Author(s) -
Barton Randall W.,
Prendergast Jay,
Kennedy Charles A.
Publication year - 1990
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.48.4.291
Subject(s) - dipeptidyl peptidase , monoclonal antibody , microbiology and biotechnology , biology , peripheral blood mononuclear cell , antigen , cell , cluster of differentiation , western blot , t cell , cell culture , antibody , enzyme , biochemistry , immunology , in vitro , gene , immune system , genetics
The monoclonal antibodies, Ta1 and IOT15, define T cell activation cell surface markers and have been assigned to the CD26 leukocyte differentiation antigen cluster. Dipeptidyl peptidase IV (DPP IV, EC 3.4.14.5) is an exoaminopeptidase that, among leukocytes, is expressed almost exclusively on activated T cells. Comparative binding studies showed that the Ta1 mAb binds to DPP IV purified from human placenta as well as in extracts of the human YT lymphoid cell line and of CD3 stimulated normal human peripheral blood mononuclear cells. The mAb IOT15 did not bind to DPP IV from any source even upon repeated incubations. Western blot analysis of YT cell extracts revealed that Ta1 and IOT15 bound to distinctly different molecular weight molecules. Immunofluorescent cell surface capping experiments showed that capping of the IOT15 did not alter the surface distribution of the Ta1 fluorescence. The capping results combined with the DPP IV binding results indicate that IOT15 and Tal mAb's bind to different, apparently unassociated, molecules on the surface of T cells and that only Ta1 binds the T cell surface enzyme DPP IV.