Is CD26/dipeptidyl peptidase IV a really important molecule in T cell activation of a certain rat strain?
A new monoclonal antibody (MS-7 mAb) was raised to investigate the real role of the membrane-associated molecule CD26/dipeptidyl peptidase IV (DPP IV; EC 3.4.14.5), which transduces activation signals in T cells. A strain of rats which is deficient in DPP IV was used. MS-7 mAb recognized DPP IV (110 kDa) and its 60 kDa fragment, starting at the 281st residue corresponding to the extracellular one comprising the active-site sequence Gly-X-Ser631-X-Gly of DPP IV. MS-7 mAb recognized CD26 on T cells of DPP IV+ rats both before and after mitogen activation. CD26 expression and DPP IV enzyme activity are increased on T cells following their activation; nevertheless, no CD26 was expressed on T cells of DPP IV- rats, and no DPP IV enzyme activity was detected either before or after mitogen activation. In addition, MS-7 mAb inhibited the mitogen-stimulated proliferation of DPP IV+ rats, but did not affect that of DPP IV- rats. These results suggest that CD26/DPP IV is not a necessary molecule in T cell activation, and that there is some other bypass in T cell activation of DPP IV- rats.
Iwaki-Egawa
S
S
Department of Clinical Biochemistry, Hokkaido Institute of Pharmaceutical Sciences, Otaru, Japan.
Watanabe
Y
Y
Fujimoto
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000494:pharmacology; D001667:Binding, Competitive / Q000276:immunology; D002462:Cell Membrane / Q000737:chemistry / Q000276:immunology; D002469:Cell Separation; D018819:Dipeptidyl Peptidase 4 / Q000276:immunology / Q000502:physiology*; D004789:Enzyme Activation / Q000276:immunology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000276:immunology; D010835:Phytohemagglutinins / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D013045:Species Specificity; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*
D000911:Antibodies, Monoclonal; D010835:Phytohemagglutinins; D018819:Dipeptidyl Peptidase 4