scholarly journals Partial signaling by CD8+ T cells in response to antagonist ligands.

1996 ◽  
Vol 184 (1) ◽  
pp. 149-157 ◽  
Author(s):  
C Reis e Sousa ◽  
E H Levine ◽  
R N Germain
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tyrosine Phosphorylation ◽  
Cd8 T Cells ◽  
Inositol Phosphates ◽  
Partial Agonist ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Cd4 Cells ◽  
Partial Agonists

Structural variants of an agonist peptide-major histocompatibility complex (MHC) molecule ligand can show partial agonist and/or antagonist properties. A number of such altered ligands appear to act as pure antagonists. They lack any detectable ability to induce T cell effector function and have been described as unable to induce calcium transients and turnover of inositol phosphates. This has been interpreted as an inability of these ligands to initiate any T cell receptor (TCR)-dependent signal transduction, with their antagonist properties ascribed to competition with offered agonist for TCR occupancy. Yet antagonists for mature CD8+ T cells can induce positive selection of thymocytes, implying active induction of T cell differentiation events, and partial agonists or agonist/antagonist combinations elicit a distinctive pattern of early TCR-associated tyrosine phosphorylation events in CD4+ T cells. We have therefore directly examined proximal TCR signaling in a CD8+ T cell line in response to various related ligands. TCR engagement with natural peptide-MHC class I agonist resulted in the same pattern of early TCR-associated tyrosine phosphorylation events as seen with CD4+ cells, including accumulation of both the p21 and p23 forms of phosphorylated zeta, phosphorylation of CD3 epsilon, and association of phosphorylated ZAP-70 with the TCR. Two antagonists that lacked the ability to induce any detectable CTL effector response (cytolysis, esterase release, gamma interferon secretion, interleukin-2 receptor alpha upregulation) were nevertheless found to also induce TCR-dependent phosphorylation events. In these cases, there was preferential accumulation of the p21 form of phospho-zeta without net phosphorylation of CD3 epsilon, as well as the association of nonphosphorylated ZAP-70 kinase with the receptor. These data show that variant ligands induce similar TCR-dependent phosphorylation events in CD8+ T cells as first observed in CD4+ cells. More importantly, they demonstrate that some putatively pure antagonists are actually a subset of partial agonists able to induce intracellular biochemical changes through the TCR. This delivery of a partial signal by antagonists raises the possibility that antagonism in some cases may result from active interference with stimulation of effector activity by agonist in mature T cells, while the same variant signal could selectively trigger intracellular events that allow positive without negative selection in thymocytes.

scholarly journals The Efficiency of CD4 Recruitment to Ligand-engaged TCR Controls the Agonist/Partial Agonist Properties of Peptide–MHC Molecule Ligands

1997 ◽  
Vol 185 (2) ◽  
pp. 219-230 ◽  
Author(s):  
Joaquín Madrenas ◽  
Luan A. Chau ◽  
Judy Smith ◽  
Jeffrey A. Bluestone ◽  
Ronald N. Germain
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class Ii ◽  
Partial Agonist ◽  
Interleukin 2 ◽  
Class Ii ◽  
Wild Type ◽  
Functional Responses ◽  
Mhc Molecules ◽  
Partial Agonists

One hypothesis seeking to explain the signaling and biological properties of T cell receptor for antigen (TCR) partial agonists and antagonists is the coreceptor density/kinetic model, which proposes that the pharmacologic behavior of a TCR ligand is largely determined by the relative rates of (a) dissociation of ligand from an engaged TCR and (b) recruitment of lck-linked coreceptors to this ligand-engaged receptor. Using several approaches to prevent or reduce the association of CD4 with occupied TCR, we demonstrate that consistent with this hypothesis, the biological and biochemical consequence of limiting this interaction is to convert typical agonists into partial agonist stimuli. Thus, adding anti-CD4 antibody to T cells recognizing a wild-type peptide–MHC class II ligand leads to disproportionate inhibition of interleukin-2 (IL-2) relative to IL-3 production, the same pattern seen using a TCR partial agonist/antagonist. In addition, T cells exposed to wild-type ligand in the presence of anti-CD4 antibodies show a pattern of TCR signaling resembling that seen using partial agonists, with predominant accumulation of the p21 tyrosine-phosphorylated form of TCR-ζ, reduced tyrosine phosphorylation of CD3ε, and no detectable phosphorylation of ZAP-70. Similar results are obtained when the wild-type ligand is presented by mutant class II MHC molecules unable to bind CD4. Likewise, antibody coligation of CD3 and CD4 results in an agonist-like phosphorylation pattern, whereas bivalent engagement of CD3 alone gives a partial agonist-like pattern. Finally, in accord with data showing that partial agonists often induce T cell anergy, CD4 blockade during antigen exposure renders cloned T cells unable to produce IL-2 upon restimulation. These results demonstrate that the biochemical and functional responses to variant TCR ligands with partial agonist properties can be largely reproduced by inhibiting recruitment of CD4 to a TCR binding a wild-type ligand, consistent with the idea that the relative rates of TCR–ligand disengagement and of association of engaged TCR with CD4 may play a key role in determining the pharmacologic properties of peptide–MHC molecule ligands. Beyond this insight into signaling through the TCR, these results have implications for models of thymocyte selection and the use of anti-coreceptor antibodies in vivo for the establishment of immunological tolerance.

Thymic selection and peptide-induced activation of T cell receptor-transgenic CD8 T cells in interleukin-2-deficient mice

1994 ◽  
Vol 24 (10) ◽  
pp. 2317-2322 ◽  
Author(s):  
Susanne Krämer ◽  
Clio Mamalaki ◽  
Ivan Horak ◽  
Anneliese Schimpl ◽  
Dimitris Kioussis ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cd8 T Cells ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Thymic Selection ◽  
Deficient Mice

scholarly journals The Trend of TIM3 Expression on T Cells in Patients With Nontuberculous Mycobacterial Lung Disease: From Immune Cell Dysfunction to Clinical Severity

2021 ◽  
Vol 12 ◽  
Author(s):  
Ping-Huai Wang ◽  
Ming-Fang Wu ◽  
Chi-Yu Hsu ◽  
Sheng-Wei Pan ◽  
Chin-Chung Shu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lung Disease ◽  
Cd8 T Cells ◽  
Cell Apoptosis ◽  
Interleukin 2 ◽  
Clinical Severity ◽  
Cd4 Cells ◽  
Nontuberculous Mycobacterial Lung Disease ◽  
Tnf Α

BackgroundThe incidence of nontuberculous mycobacterial lung disease (NTM-LD) is increasing worldwide. Immune exhaustion has been reported in NTM-LD, but T-cell immunoglobulin and mucin domain-containing protein 3 (TIM3), a co-inhibitory receptor on T cells, has been scarcely studied.MethodsPatients with NTM-LD and healthy controls were prospectively recruited from July 2014 to August 2019 at three tertiary referral centers in Taiwan. We examined TIM3 expression on the T cells from the participants using flow cytometry. TIM3 expression was analyzed for different disease statuses and after treatment. The apoptosis and cytokine profiles were analyzed according to the TIM3 expression.ResultsAmong enrolled subjects (47 patients and 46 controls), TIM3 on CD4+ cells (6.44% vs. 4.12%, p = 0.028) and CD8+ cells (18.47% vs. 9.13%, p = 0.003) were higher in NTM-LD patients than in the controls. The TIM3 level on CD4+ and CD8+ T cells was positively associated with T-cell apoptosis in the NTM-LD patients. In stimulating peripheral blood mononuclear cells using PMA plus ionomycin, a high TIM3 level on T cells correlated with low interleukin-2 and tumor necrosis factor-alpha (TNF-α) on CD4+ cells and interferon-gamma and TNF-α on CD8+ T cells. For clinical manifestation, low body mass index (BMI), positive sputum acid-fast smear, and high radiographic score correlated with high TIM3 expression on T cells. After NTM treatment, TIM3+ decreased significantly on CD4+ and CD8+ T cells.ConclusionsIn patients with NTM-LD, TIM3+ expression increased over CD4+ and CD8+ T cells and correlated with cell apoptosis and specific cytokine attenuation. Clinically, TIM3+ T cells increased in patients with low BMI, high disease extent, and high bacilli burden but decreased after treatment.

scholarly journals Tyrosine phosphorylation of a c-Src-like protein is increased in membranes of CD4- CD8- T lymphocytes from lpr/lpr mice

1989 ◽  
Vol 9 (11) ◽  
pp. 4914-4922
Author(s):  
T Katagiri ◽  
J P Ting ◽  
R Dy ◽  
C Prokop ◽  
P Cohen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Tyrosine Phosphorylation ◽  
Cd8 T Cells ◽  
Fold Increase ◽  
Cell Receptor ◽  
Proteolytic Cleavage ◽  
Two Dimensional ◽  
Two Dimensional Gel Electrophoresis

Mice homozygous for the autosomal recessive lpr gene have a disorder that results in autoimmunity and massive accumulation of T lymphocytes lacking CD4 and CD8 surface markers. These abnormal T cells exhibit constitutive tyrosine phosphorylation of a component of the CD3-T-cell receptor complex. We compared membrane tyrosine phosphorylation in lpr/lpr CD4- CD8- T cells and control T cells, lpr membranes exhibited a 7.3-fold increase (n = 16) in tyrosine phosphorylation of a 60-kilodalton protein. The increase was correlated with the Lpr but not the CD4- CD8- phenotype in that p60 phosphorylation was not increased in membranes from normal CD4- CD8- thymocytes. To identify the p60 in lpr cells, we examined the activity of several T-cell tyrosine-specific protein kinases. p56lck phosphorylation was only slightly increased in lpr membranes (2.2-fold; n = 16). Phorbol ester treatment of intact T cells before membrane isolation caused p56lck to migrate as pp60lck; however, pp60lck could be clearly distinguished from the pp60 in lpr cells by two-dimensional gel electrophoresis. The pp60 from lpr cells exhibited several isoforms at pH approximately 6.3 to 6.5. Although on two-dimensional gels pp60c-src had a pI (6.4 to 6.8) within a similar region, p60c-src mRNA, protein, and kinase activities were not increased in lpr cells. In addition, staphylococcal V8 proteolytic cleavage of the lpr pp60 isolated on two-dimensional gels yielded two major fragments, a pattern distinct from that of pp60c-src. However, by using an antiserum against the C-terminal sequence of c-Src and other related kinases, including p59fyn, the pp60 could be immunoprecipitated in greater amounts from lpr than from control T cells. When pp59(fyn) was selectively immunoprecipitated from T-cell membranes with specific antisera, its molecular weight, proteolytic cleavage pattern, and behavior on two-dimensional gels were identical to those of the pp60 from lpr cells. We conclude that p59(fyn) phosphorylation is increased in membranes from lpr/lpr CD4(-) CD8(-) T cells and that the increase is correlated with constitutive tyrosine phosphorylation and perhaps with the expansion of this unusual T-cell population.

scholarly journals Tyrosine phosphorylation of a c-Src-like protein is increased in membranes of CD4- CD8- T lymphocytes from lpr/lpr mice.

1989 ◽  
Vol 9 (11) ◽  
pp. 4914-4922 ◽  
Author(s):  
T Katagiri ◽  
J P Ting ◽  
R Dy ◽  
C Prokop ◽  
P Cohen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Tyrosine Phosphorylation ◽  
Cd8 T Cells ◽  
Fold Increase ◽  
Cell Receptor ◽  
Proteolytic Cleavage ◽  
Two Dimensional ◽  
Two Dimensional Gel Electrophoresis

Mice homozygous for the autosomal recessive lpr gene have a disorder that results in autoimmunity and massive accumulation of T lymphocytes lacking CD4 and CD8 surface markers. These abnormal T cells exhibit constitutive tyrosine phosphorylation of a component of the CD3-T-cell receptor complex. We compared membrane tyrosine phosphorylation in lpr/lpr CD4- CD8- T cells and control T cells, lpr membranes exhibited a 7.3-fold increase (n = 16) in tyrosine phosphorylation of a 60-kilodalton protein. The increase was correlated with the Lpr but not the CD4- CD8- phenotype in that p60 phosphorylation was not increased in membranes from normal CD4- CD8- thymocytes. To identify the p60 in lpr cells, we examined the activity of several T-cell tyrosine-specific protein kinases. p56lck phosphorylation was only slightly increased in lpr membranes (2.2-fold; n = 16). Phorbol ester treatment of intact T cells before membrane isolation caused p56lck to migrate as pp60lck; however, pp60lck could be clearly distinguished from the pp60 in lpr cells by two-dimensional gel electrophoresis. The pp60 from lpr cells exhibited several isoforms at pH approximately 6.3 to 6.5. Although on two-dimensional gels pp60c-src had a pI (6.4 to 6.8) within a similar region, p60c-src mRNA, protein, and kinase activities were not increased in lpr cells. In addition, staphylococcal V8 proteolytic cleavage of the lpr pp60 isolated on two-dimensional gels yielded two major fragments, a pattern distinct from that of pp60c-src. However, by using an antiserum against the C-terminal sequence of c-Src and other related kinases, including p59fyn, the pp60 could be immunoprecipitated in greater amounts from lpr than from control T cells. When pp59(fyn) was selectively immunoprecipitated from T-cell membranes with specific antisera, its molecular weight, proteolytic cleavage pattern, and behavior on two-dimensional gels were identical to those of the pp60 from lpr cells. We conclude that p59(fyn) phosphorylation is increased in membranes from lpr/lpr CD4(-) CD8(-) T cells and that the increase is correlated with constitutive tyrosine phosphorylation and perhaps with the expansion of this unusual T-cell population.

Role of NKG2D signaling in the cytotoxicity of activated and expanded CD8+ T cells

Blood ◽  
2004 ◽  
Vol 103 (8) ◽  
pp. 3065-3072 ◽  
Author(s):  
Michael R. Verneris ◽  
Mobin Karami ◽  
Jeanette Baker ◽  
Anishka Jayaswal ◽  
Robert S. Negrin
Keyword(s):  
T Cells ◽  
Cd8 T Cells ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Malignant Cell ◽  
Leukemic Cells ◽  
Target Cells ◽  
High Dose ◽  
Effector Cells ◽  
Nkg2d Expression

Abstract Activating and expanding T cells using T-cell receptor (TCR) cross-linking antibodies and interleukin 2 (IL-2) results in potent cytotoxic effector cells capable of recognizing a broad range of malignant cell targets, including autologous leukemic cells. The mechanism of target cell recognition has previously been unknown. Recent studies show that ligation of NKG2D on natural killer (NK) cells directly induces cytotoxicity, whereas on T cells it costimulates TCR signaling. Here we demonstrate that NKG2D expression is up-regulated upon activation and expansion of human CD8+ T cells. Antibody blocking, redirected cytolysis, and small interfering RNA (siRNA) studies using purified CD8+ T cells demonstrate that cytotoxicity against malignant target cells occurs through NKG2D-mediated recognition and signaling and not through the TCR. Activated and expanded CD8+ T cells develop cytotoxicity after 10 to 14 days of culture, coincident with the expression of the adapter protein DAP10. T cells activated and expanded in low (30 U/mL) and high (300 U/mL) concentrations of IL-2 both up-regulated NKG2D expression equally, but only cells cultured in high-dose IL-2 expressed DAP10 and were cytotoxic. Collectively these results establish that NKG2D triggering accounts for the majority of major histocompatibility complex (MHC)–unrestricted cytotoxicity of activated and expanded CD8+ T cells, likely through DAP10-mediated signaling. (Blood. 2004;103: 3065-3072)

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