scholarly journals Telomerase regulation during entry into the cell cycle in normal human T cells.

1996 ◽  
Vol 7 (9) ◽  
pp. 1443-1454 ◽  
Author(s):  
K J Buchkovich ◽  
C W Greider
Keyword(s):  
Cell Cycle ◽  
T Cells ◽  
T Cell ◽  
Cell Receptor ◽  
Telomerase Activity ◽  
Quiescent Cells ◽  
Human T Cells ◽  
Somatic Tissues ◽  
Normal Human Cell ◽  
Normal Human

Telomerase activity is involved in telomere length maintenance. Leukocytes, unlike many human somatic tissues, have detectable telomerase activity. These cells provide a normal human cell type in which to study telomerase. We studied the regulation of telomerase activity and the telomerase RNA component as leukocytes were stimulated to enter the cell cycle. In primary human leukocytes stimulated with phytohemagglutinin, telomerase activity increased > 10-fold as naturally quiescent cells entered the cell cycle. Antibodies to the T cell receptor (TCR)/CD3 complex and the costimulatory CD28 receptor induced telomerase activity in a T cell-enriched population of cells. Rapamycin, an immunosuppressant that blocks TCR/CD3 signal transduction pathways and cdk2 activation, blocked telomerase induction. Hydroxyurea, an inhibitor of S phase, did not block cdk2 kinase activity or telomerase activation. In summary, telomerase is regulated in G1 phase as normal human T cells enter the cell cycle.

scholarly journals T Cell Receptor-induced Activation and Apoptosis In Cycling Human T Cells Occur throughout the Cell Cycle

1999 ◽  
Vol 10 (12) ◽  
pp. 4441-4450 ◽  
Author(s):  
Michael Karas ◽  
Tal Z. Zaks ◽  
Liu JL ◽  
Derek LeRoith
Keyword(s):  
Cell Cycle ◽  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
T Cell Receptor ◽  
Fas Ligand ◽  
Cell Receptor ◽  
Receptor Activation ◽  
Activation Induced Cell Death ◽  
Human T Cells

Previous studies have found conflicting associations between susceptibility to activation-induced cell death and the cell cycle in T cells. However, most of the studies used potentially toxic pharmacological agents for cell cycle synchronization. A panel of human melanoma tumor-reactive T cell lines, a CD8+ HER-2/neu-reactive T cell clone, and the leukemic T cell line Jurkat were separated by centrifugal elutriation. Fractions enriched for the G0–G1, S, and G2–M phases of the cell cycle were assayed for T cell receptor-mediated activation as measured by intracellular Ca2+flux, cytolytic recognition of tumor targets, and induction of Fas ligand mRNA. Susceptibility to apoptosis induced by recombinant Fas ligand and activation-induced cell death were also studied. None of the parameters studied was specific to a certain phase of the cell cycle, leading us to conclude that in nontransformed human T cells, both activation and apoptosis through T cell receptor activation can occur in all phases of the cell cycle.

scholarly journals Characterization of human T cells reactive with the Mycoplasma arthritidis-derived superantigen (MAM): generation of a monoclonal antibody against V beta 17, the T cell receptor gene product expressed by a large fraction of MAM-reactive human T cells.

1991 ◽  
Vol 174 (4) ◽  
pp. 891-900 ◽  
Author(s):  
S M Friedman ◽  
M K Crow ◽  
J R Tumang ◽  
M Tumang ◽  
Y Q Xu ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Activity ◽  
Cell Receptor ◽  
Cytotoxic T Cell ◽  
Mycoplasma Arthritidis ◽  
Human T Cells

While all known microbial superantigens are mitogenic for human peripheral blood lymphocytes (PBL), the functional response induced by Mycoplasma arthritidis-derived superantigen (MAM) is unique in that MAM stimulation of PBL consistently results in T cell-dependent B cell activation characterized by polyclonal IgM and IgG production. These immunostimulatory effects of MAM on the humoral arm of the human immune system warranted a more precise characterization of MAM-reactive human T cells. Using an uncloned MAM reactive human T cell line as immunogen, we have generated a monoclonal antibody (mAb) (termed C1) specific for the T cell receptor V beta gene expressed by the major fraction of MAM-reactive human T cells, V beta 17. In addition, a V beta 17- MAM-reactive T cell population exists, assessed by MAM, induced T cell proliferation and cytotoxic T cell activity. mAb C1 will be useful in characterizing the functional properties of V beta 17+ T cells and their potential role in autoimmune disease.

scholarly journals Structure and specificity of T cell receptor gamma/delta on major histocompatibility complex antigen-specific CD3+, CD4-, CD8- T lymphocytes.

1988 ◽  
Vol 168 (5) ◽  
pp. 1899-1916 ◽  
Author(s):  
J A Bluestone ◽  
R Q Cron ◽  
M Cotterman ◽  
B A Houlden ◽  
L A Matis
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Line ◽  
Gene Segment ◽  
Cell Receptor ◽  
Gamma Delta ◽  
Human T Cells ◽  
T Cell Lines ◽  
Gamma Delta T Cell ◽  
Delta Cells

Analyses of TCR-bearing murine and human T cells have defined a unique subpopulation of T cells that express the TCR-gamma/delta proteins. The specificity of TCR-gamma/delta T cells and their role in the immune response have not yet been elucidated. Here we examine alloreactive TCR-gamma/delta T cell lines and clones that recognize MHC-encoded antigens. A BALB/c nu/nu (H-2d)-derived H-2k specific T cell line and derived clones were both cytolytic and released lymphokines after recognition of a non-classical H-2 antigen encoded in the TL region of the MHC. These cells expressed the V gamma 2/C gamma 1 protein in association with a TCR-delta gene product encoded by a Va gene segment rearranged to two D delta and one J delta variable elements. A second MHC-specific B10 nu/nu (H-2b) TCR-gamma/delta T cell line appeared to recognize a classical H-2D-encoded MHC molecule and expressed a distinct V gamma/C gamma 4-encoded protein. These data suggest that many TCR-gamma/delta-expressing T cells may recognize MHC-linked antigens encoded within distinct subregions of the MHC. The role of MHC-specific TCR-gamma/delta cells in immune responses and their immunological significance are discussed.

Expression of T-cell receptor α and β variable genes in normal and malignant human T cells

1993 ◽  
Vol 84 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Huaizhong Hu ◽  
Màrio Rui Queirò ◽  
Marcel G. J. Tilanus ◽  
Roel A. Weger ◽  
Henk-Jan Schuurman
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Human T Cells ◽  
Variable Genes

scholarly journals The discriminatory power of the T cell receptor

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Johannes Pettmann ◽  
Anna Huhn ◽  
Enas Abu Shah ◽  
Mikhail A Kutuzov ◽  
Daniel B Wilson ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptors ◽  
Cell Receptor ◽  
Discriminatory Power ◽  
Factors Affecting ◽  
Surface Receptors ◽  
Human T Cells ◽  
Conventional Cell ◽  
Kinetic Proofreading

T cells use their T-cell receptors (TCRs) to discriminate between lower-affinity self and higher-affinity non-self pMHC antigens. Although the discriminatory power of the TCR is widely believed to be near-perfect, technical difficulties have hampered efforts to precisely quantify it. Here, we describe a method for measuring very low TCR/pMHC affinities, and use it to measure the discriminatory power of the TCR, and the factors affecting it. We find that TCR discrimination, although enhanced compared with conventional cell-surface receptors, is imperfect: primary human T cells can respond to pMHC with affinities as low as KD ~1 mM. The kinetic proofreading mechanism fit our data, providing the first estimates of both the time delay (2.8 s) and number of biochemical steps (2.67) that are consistent with the extraordinary sensitivity of antigen recognition. Our findings explain why self pMHC frequently induce autoimmune diseases and anti-tumour responses, and suggest ways to modify TCR discrimination.

scholarly journals T Cell Receptor Transfection Shows Non-HLA-Restricted Recognition of Nickel by CD8+ Human T Cells to be Mediated by αβ T Cell Receptors

2003 ◽  
Vol 121 (3) ◽  
pp. 496-501 ◽  
Author(s):  
Corinne Moulon ◽  
Yoanna Choleva ◽  
Hermann-Josef Thierse ◽  
Doris Wild ◽  
Hans Ulrich Weltzien
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Receptors ◽  
Cell Receptor ◽  
Cell Receptors ◽  
Human T Cells
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