- The interaction of T cells with antigen (Ag) leads to the generation of effector and memory cells. Memory cells have characteristic cell surface marker profiles, and are able to rapidly respond to recall antigens. CD4+ memory cells accumulate in the periphery during aging, following chronic stimulation, and in autoimmune diseases like rheumatoid arthritis (RA). Recently, the applicant has found that the ecto-enzyme gamma glutamyl transpeptidase (GGT) is up-regulated upon T cell activation, and is highly expressed by memory T cells. High levels of GGT are also found in T cells with the capacity to cross endothelial barriers, and on resting peripheral T cells in patients with RA. The role of this enzyme in lymphocyte biology is unclear, but it may be important in maintenance of intracellular re-dox potential and signaling events.
The aims of this application are to 1) determine whether GGT is a better marker of memory T cells than previously described surface Ags; 2) determine the role of GGT in T cell biology; and 3) determine the role of GGT in transendothelial migration of peripheral blood T cells. Experiments proposed include flow cytometric analysis, functional responses of GGT expressing cells to determine if these cells indeed have memory function; and using various strategies to disrupt enzymatic activity, the applicant will test the effect of GGT on activation, growth, and apoptosis. These experiments will provide a thorough description of GGT function in lymphocytes, and should be useful in expanding our knowledge about the memory T cell compartment. GGT also may be a potential target in future immunotherapy strategies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI042772-04
Application #
6510801
Study Section
General Medicine A Subcommittee 2 (GMA)
Program Officer
Mallia, Conrad M
Project Start
1999-03-15
Project End
2004-02-28
Budget Start
2002-03-01
Budget End
2004-02-28
Support Year
4
Fiscal Year
2002
Total Cost
$241,419
Indirect Cost
Name
University of Texas Sw Medical Center Dallas
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Dallas
State
TX
Country
United States
Zip Code
75390
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Karp, D R; Shimooku, K; Lipsky, P E (2001) Expression of gamma-glutamyl transpeptidase protects ramos B cells from oxidation-induced cell death. J Biol Chem 276:3798-804
Karp, D R; Carlisle, M L; Mobley, A B et al. (1999) Gamma-glutamyl transpeptidase is up-regulated on memory T lymphocytes. Int Immunol 11:1791-800
Henson, S E; Nichols, T C; Holers, V M et al. (1999) The ectoenzyme gamma-glutamyl transpeptidase regulates antiproliferative effects of S-nitrosoglutathione on human T and B lymphocytes. J Immunol 163:1845-52