Determination and Quantitation of Cytotoxic T Cell-Mediated Cell Death.

Cytotoxic T cell-induced cell death is well documented. Cytotoxic T cell releases various cytolytic proteins. The cytolytic proteins induce target cell death.

Phentermine interference and high L-methamphetamine concentration problems in GC-EI-MS SIM Analyses of R-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride-derivatized amphetamines and methamphetamines†.

In order to achieve chromatographic separation, urine samples shown to be initially positive for amphetamines and methamphetamines in US Department of Defense immunoassays are derivatized with R-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride (R-(-)-MTPA) prior to gas chromatography-electron impact-mass spectrometry (GC-EI-MS) analysis. Phentermine, a member of the phenethylamine class of drugs and a common appetite suppressant, interferes with GC-EI-MS assays of R-(-)-MTPA-derivatized d-amphetamine, degrading the chromatography of the internal standard and analyte ions and skewing concentration calculations. Additionally, when specimens with high concentrations of l-methamphetamine are derivatized with R-(-)-MTPA, signal peaks have the potential to be misidentified by integration software as d-methamphetamine.

CD134/CD137 dual costimulation-elicited IFN-γ maximizes effector T-cell function but limits Treg expansion.

T-cell tolerance to tumor antigens represents a major hurdle in generating tumor immunity. Combined administration of agonistic monoclonal antibodies (mAbs) to the costimulatory receptors CD134 plus CD137 can program T-cells responding to tolerogenic antigen to undergo expansion, and effector T-cell differentiation, and also elicits tumor immunity. Nevertheless, CD134 and CD137 agonists can also engage inhibitory immune components.

CD134 plus CD137 dual costimulation induces Eomesodermin in CD4 T cells to program cytotoxic Th1 differentiation.

Cytotoxic CD4 Th1 cells are emerging as a therapeutically useful T cell lineage that can effectively target tumors, but until now the pathways that govern their differentiation have been poorly understood. We demonstrate that CD134 (OX40) costimulation programs naive self- and virus-reactive CD4 T cells to undergo in vivo differentiation into cytotoxic Th1 effectors. CD137 (4-1BB) costimulation maximized clonal expansion, and IL-2 was necessary for cytotoxic Th1 differentiation.

The E3 ubiquitin ligase Cbl-b regulates expansion but not functional activity of self-reactive CD4 T cells.

Cbl-b is an E3 ubiquitin ligase that limits Ag responsiveness in T cells by targeting TCR-inducible signaling molecules. Cbl-b deficiency thus renders T cells hyperresponsive to antigenic stimulation and predisposes individuals toward developing autoimmunity. In part because Cbl-b(-/-) T cells do not require CD28 costimulation to become activated, and insufficient costimulation is a critical parameter that confers anergy induction over effector differentiation, it has been hypothesized that Cbl-b(-/-) T cells are resistant to anergy.

Nonuniform sampling and spectral aliasing.

The Nyquist theorem stipulates the largest sampling interval sufficient to avoid aliasing is the reciprocal of the spectral bandwidth. When data are not sampled uniformly, the Nyquist theorem no longer applies, and aliasing phenomena become more complex. For samples selected from an evenly spaced grid, signals that are within the nominal bandwidth of the grid can give rise to aliases.

In vitro and in vivo differentiated effector CD8 T cells display divergent histone acetylation patterns within the Ifng locus.

Epigenetic remodeling of genes encoding effector cytokines that permit accessibility to the transcriptional machinery is a central event in the differentiation of naive T cells into effectors that can attack pathogens and tumors. Covalent modifications of histones that cause a loosening of nucleosomal structures occur not only in promoter regions, but also at upstream and downstream enhancer elements that integrate various cellular stimuli to modulate the rate of transcriptional initiation. This knowledge derives mostly from the analysis of in vitro differentiated effector T cells.

Self-antigen prevents CD8 T cell effector differentiation by CD134 and CD137 dual costimulation.

We compared how CD4 vs CD8 cells attain the capacity to express the effector cytokine IFN-gamma under both immunogenic and tolerogenic conditions. Although the Ifng gene locus was epigenetically repressed in naive Ag-inexperienced CD4 cells, it had already undergone partial remodeling toward a transcriptionally competent configuration in naive CD8 cells. After TCR stimulation, CD8 cells fully remodeled the Ifng locus and gained the capacity to express high levels of IFN-gamma more rapidly than CD4 cells.

Steady state dendritic cells present parenchymal self-antigen and contribute to, but are not essential for, tolerization of naive and Th1 effector CD4 cells.

Bone marrow-derived APC are critical for both priming effector/memory T cell responses to pathogens and inducing peripheral tolerance in self-reactive T cells. In particular, dendritic cells (DC) can acquire peripheral self-Ags under steady state conditions and are thought to present them to cognate T cells in a default tolerogenic manner, whereas exposure to pathogen-associated inflammatory mediators during the acquisition of pathogen-derived Ags appears to reprogram DCs to prime effector and memory T cell function. Recent studies have confirmed the critical role of DCs in priming CD8 cell effector responses to certain pathogens, although the necessity of steady state DCs in programming T cell tolerance to peripheral self-Ags has not been directly tested.