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At least 91 records · Page 5Linked to original sources
PubMed1999

A single cell analysis of TCR AV24AJ18+ DN T cells.

The T-cell receptor (TCR) BV gene of human TCR AV24+ double-negative (DN) T cells, a novel subset of natural killer (NK) T cells, was investigated by single-cell sorting and single-cell polymerase chain reaction (PCR) methods. Seven of eleven TCR AV24+ DN T-cell clones utilized TCR BV8, three BV9, and one BV6. Six of seven TCR AV24/BV8+ DN T-cell clones had identical TCR beta and alpha chains, indicating that they were the same clone. All three TCR AV24/BV9+ DN T-cell clones also demonstrated the same amino acids in the CDR3 region. These findings strongly suggest that the usage of TCR beta and alpha chains on TCR AV24+ DN T cells is extremely restricted, supporting the notion that these cells recognize highly limited T-cell epitopes on antigens. All TCR AV24+ clones expressed the NKR-P1A mRNA, and so were true NK T cells. IL-2 and IL-4 mRNAs were detected in all clones, suggesting that the majority of these cells were Th0-type T cells. Six clones overexpressed Fas-ligand (Fas-L) mRNA and Fas antigen was detected on all clones at the mRNA level. In conclusion, TCR AV24+ DN T cells might recognize restricted T-cell epitopes on antigens and function as Th0-type T cells, inducer cells to Th1- or Th2-type T cells (regulatory T cells), and as Fas-L-positive cytolytic T cells.

Amino Acid Sequence↗
PubMed2000

A single cell analysis of Fas ligand positive T cells in rheumatoid synovial fluid.

OBJECTIVE: To investigate the function of Fas ligand (Fas-L) positive T cells in rheumatoid synovium, we analyzed the T cell receptor (TCR) CDR3 region and examined the expression of cytokines in both Fas-L+ and Fas-L- single T cells. METHODS: Synovial fluid (SF) samples were collected from 2 patients with rheumatoid arthritis. TCR BV8+ T cells were sorted into a 96 well plate at a density of one cell per well. Expression of Fas-L, interferon-gamma, interleukin 2 (IL-2), IL-4, IL-6, and IL-10 was analyzed by reverse transcription-polymerase chain reaction and Southern blot and the TCR BV8 junctional region was sequenced. RESULTS: Twenty-two of 30 TCR BV8+ T cells from Patient 1 and 20 of 43 TCR BV8+ T cells from Patient 2 were Fas-L+ T cells, while the others were Fas-L-. Junctional sequence analysis showed the presence of some conserved amino acid motifs in the CDR3 region (SRQ, GFG, SSG, SGS, LGTSGTL, TLSS) in 13 clones of Fas-L+ T cells from Patient 1, whereas no conserved amino acid motif in Fas-L-T cells was found. In Patient 2, conserved amino acid motifs (PGQ, GQG, TTWGA) in the CDR3 region were found in 6 clones of Fas-L+ T cells, while only one was found in 2 clones of Fas-L-cells. In Fas-L+ T cells, 90-93% expressed both IL-2 and IL-10 mRNA. CONCLUSION: Fas-L+ TCR BV8+ T cells revealed the conserved amino acids motif in the CDR3 region, suggesting that Fas-L+ T cells might expand by antigen stimulation and play a crucial role as Th0-type T cells in triggering autoimmunity in rheumatoid synovium.

Aged↗
PubMed1999

Single-cell analysis of costimulation by B cells, endothelial cells, and fibroblasts demonstrates heterogeneity in responses of CD4(+) memory T cells.

Human endothelial cells (EC) express MHC class II molecules in vivo and are likely to be involved in presentation of antigens to CD4(+) T cells. We examined, at the single-cell level, EC presentation of superantigens to resting CD4(+) memory T cells. Within 2 h of adherence to class II+ EC early T cell activation is evidenced by translocation of nuclear factor of activated T cells (NFAT), surface expression of CD69, and synthesis of IFN-gamma and IL-2. Naive T cells are not activated. T cell activation is dependent on the prior induction of MHC class II molecules on EC and is blocked by antibodies to LFA-3 (CD58). Our data place EC along a spectrum of antigen-presenting ability. Activated B cells and macrophages trigger more cells to express cytokines than do EC and at lower antigen concentrations; EC are in turn, superior to fibroblasts or smooth muscle cells. Furthermore, the concept of activation thresholds for cytokine synthesis within T cells also extends to earlier activation events: NFAT translocation is relatively easy to trigger, as is CD69 expression; fewer cells can be triggered to express IFN-gamma and fewer still to express IL-2. EC may, therefore, contribute to a graded immune response by inducing qualitatively and quantitatively different responses than professional APC.

Antigen Presentation↗
PubMed2004

Single-cell analysis of the human NK cell response to missing self and its inhibition by HLA class I.

Natural killer (NK) cells activate quickly in response to pathogens, tumors, and allogeneic hematopoietic cell transplants. Modulating the NK cell response are clonally distributed NK cell receptors that survey cells for change in the expression of major histocompatibility complex (MHC) class I and structurally related ligands. Here the enzyme-linked immunospot (ELISPOT) assay, intracellular cytokine staining (ICS), and short-term culture were used to quantify the response of bulk NK cell populations from human donors to HLA class I-deficient 221 cells and to 221 cells transfected with single HLA class I allotypes. NK cells in cultures containing interleukin-2 (IL-2) or IL-12 exhibited specificities of HLA class I-mediated inhibition that correlated well with those previously defined using NK cell clones in long-term culture and with the frequencies of cells expressing particular inhibitory HLA class I receptors. Culture with IL-12, but not IL-2, gave an increased frequency of cells expressing CD94: NKG2A but no change in killer immunoglobulin-like receptor (KIR) expression. For some heterozygote combinations of KIR3DL1 alleles, ICS can be used to compare the functional properties of the 2 allotypes. Thus, both the low-expressing KIR3DL1*005 and the high-expressing KIR3DL1*002 gave similar inhibitory response on challenge with an HLA-B*5801 ligand. The single-cell assays developed here should facilitate future population study and clinical analysis of human NK cell regulation by MHC class I.

Antigens, CD↗
PubMed2002

Evidence for the involvement of a hematopoietic progenitor cell in systemic mastocytosis from single-cell analysis of mutations in the c-kit gene.

Mast cells are derived from multipotential hematopoietic progenitors and are clonally increased in systemic mastocytosis, a disease associated with point mutations of codon 816 (most commonly Asp816Val) of c-kit. To study the lineage relationship and the extent of expansion of cells derived from the mutated clone, we examined the occurrence of the Asp816Val c-kit mutation in genomic DNA of individual sorted peripheral blood T cells, B cells, and monocytes in patients with indolent systemic mastocytosis. The mutation was detected in varying frequencies in the genomic DNA of individual B cells and monocytes and bone marrow mast cells in patients with extensive disease. In B cells, the immunoglobulin repertoire was polyclonal, indicating that the mutation occurred before V(H)/(D)/J(H) recombination. These results show that mastocytosis is a disorder of a pluripotential hematopoietic progenitor cell that gives rise to B cells and monocytes in addition to mast cells and that the affected clone shows variable expansion in these lineages in the peripheral blood of patients with systemic mastocytosis.

Adult↗
PubMed2004

Single-cell analysis of mtDNA deletion levels in sporadic amyotrophic lateral sclerosis.

One possible cause for the neuronal loss in sporadic amyotrophic lateral sclerosis (S-ALS) is an increase of free radicals, which may produce oxidative damage to susceptible biomolecules, which, in turn, can damage the mitochondrial DNA (mtDNA). Following laser microdissection of single motor neurons from paraffin-embedded autopsy tissue, we analyzed the presence of a common mtDNA deletion, the 5 kb common deletion (CD). Spinal cord neurons showed slightly higher CD detection rate in patients than controls (94% vs 75%). No significant differences were found between patients and controls for neurons derived from other motor or non-motor regions. A PCR assay of serial DNA dilutions (10-fold) showed no CD level differences between motor neurons in S-ALS and controls. These data suggest that neuronal death in S-ALS is not associated with significant accumulation of mtDNA deletions.

Adult↗
PubMed1991

Single cell analysis of changes in cytosolic calcium induced by vitamin D3 metabolites in cultured rat mesangial cells.

The acute effects of 1,25-Dihydroxy-vitamin D3 [1,25(OH)2D3] on the concentration of cytoplasmic ionized calcium [Ca2+] of cultured rat mesangial cells were studied at the single cell level by microspectrofluorometry of fura-2-loaded cells. Addition of 1,25(OH)2D3 produced an immediate increase of [Ca2]+. This rise in [Ca2+] was sustained and similar to that caused by the Ca2+ channel agonist BAY K 8644. Comparable changes were also observed in cultured human mesangial cells. The effects of the hormone (10 (-10)-10(-7) M) were dose-dependent (62% and 285%). Only 30-40% of the cells responded to stimulation with 1,25(OH)2D3. 25OHD3 also increased Ca2+ whereas 24,25(OH)2D3 and 1aOHD3 were inactive. Addition of 1 mM CoCl2 or 2-5 microM nifedipine largely blocked the effects of 1,25(OH)2D3 suggesting the involvement of Ca2+ channel activation in the rapid 1,25(OH)2D3-induced increase in mesangial cell [Ca2+]. 45Ca uptake studies are consistent with This interpretation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1999

Single-cell analysis of glycopeptide resistance gene expression in teicoplanin-resistant mutants of a VanB-type Enterococcus faecalis.

The vanB gene cluster confers resistance to vancomycin but not to the related antibiotic teicoplanin, as the VanRB SB two-component regulatory system triggers expression of the glycopeptide resistance genes only in response to vancomycin. The VanRB regulator activates promoters PRB and PYB for transcription of the regulatory (vanRB SB) and resistance (vanYB WHB BXB) genes respectively. The gfpmut1 gene encoding a green fluorescent protein was fused to PYB to analyse promoter activation in single cells by fluorescence microscopy and flow cytometry. Characterization of 17 teicoplanin-resistant mutants indicated that amino acid substitutions on either side of the VanSB autophosphorylation site led to a constitutive phenotype. Substitutions in the membrane-associated domain resulted in a gain of function, as they allowed induction by teicoplanin. A vanSB null mutant expressed gfpmut1 at various levels under non-inducing conditions, and the majority of the bacteria were not fluorescent. Bacteria grown in the presence of vancomycin or teicoplanin were homogeneously fluorescent. The increase in the number of fluorescent bacteria resulted from induction in negative cells rather than from selection of a resistant subpopulation, indicating that VanRB was activated by cross-talk. Transglycosylase inhibition was probably the stimulus for the heterologous kinase, as moenomycin was also an inducer.

Anti-Bacterial Agents↗
PubMed2002

Single cell analysis of factor VIII-specific T cells in hemophilic mice after treatment with human factor VIII.

A multi-parameter flow-cytometry assay was established suitable for analyzing T-cell-specific cell surface markers (CD3, CD4) together with intracellular cytokines on a single cell level. This assay was used to identify the frequency and the kinetic of different populations of factor VIII (FVIII)-specific CD4+ T cells in hemophilic E-17 mice after treatment with human FVIII. A clear temporal correlation was found between the appearance of FVIII-specific CD4+ T cells in the spleen and the detection of anti-FVIII antibodies in plasma. These cells and antibodies were detectable in all experiments after two doses of FVIII and in a few even after a single dose. The IFN-gamma-producing T cells were the most prominent type of FVIII-specific T cells suggesting Th1-type T cells have an important role in regulating the anti-FVIII immune response in E-17 mice. IL-10-producing T cells were the second most dominant type. They were detectable after two doses of FVIII and increased in frequency after four. Cytokine co-expression studies analyzing IL-10 and IFN-gamma in the same cell indicated that there might be at least two types of IL-10 positive T cells, those cells that produce IL-10 only and in addition cells that produce IL-10 and IFN-gamma. Furthermore, FVIII-specific T cells producing IL-2 were found in all experiments after two doses of FVIII. In a few experiments IL-4-producing T cells were seen but in most experiments they were not detectable. In contrast, IL-4 could be found in supernatants of in vitro restimulated CD8- spleen cells.

Animals↗
PubMed1996

Single-cell analysis of gene expression in the nervous system. Measurements at the edge of chaos.

The characteristic functions of tissues and organs result from the integrated activity of individual cells. Nowhere is this more evident than in the nervous system, where the activities of single neurons communicating via electrical and chemical signals mediate complex functions, such as learning and memory. The past decade has seen an explosion in the identification of genes encoding proteins, such as voltage-gated channels and neurotransmitter receptors, responsible for neuronal excitability. These studies have highlighted the fact that even within a neuroanatomically defined region, the coexistence of multiple cell types makes it difficult, if not impossible, to correlate patterns of gene expression with function. The recent development of techniques sensitive enough to study gene expression at the single-cell level promises to break this bottleneck to our further understanding. Using examples taken from our own laboratories and the work of others, we review these techniques, their application, and discuss some of the difficulties associated with the interpretation of the data.

Animals↗
PubMed2006

Single-cell analysis of glucocorticoid receptor action reveals that stochastic post-chromatin association mechanisms regulate ligand-specific transcription.

The glucocorticoid receptor (GR) dynamically interacts with response elements in the mouse mammary tumor virus (MMTV) promoter to regulate steroid-dependent transcription. In a clonal mammary carcinoma cell line containing a tandem array of MMTV promoter-reporter gene cassettes integrated at a single genomic locus, direct binding of a green fluorescent protein (GFP)-GR fusion protein to the MMTV regulatory elements can be observed in living cells. After ligand treatment, MMTV-dependent transcription in individual cells was detected by RNA fluorescence in situ hybridization (FISH). High-resolution fluorescence images were acquired from large numbers of randomly selected cells. Images were analyzed with a novel automated computer algorithm, measuring the RNA FISH signal and the relative GFP-GR fluorescence intensity at the MMTV array for each cell. Although dexamethasone increased the mean RNA FISH signal approximately 10-fold, RU486 produced only about a 2-fold induction, as expected for this mixed antagonist. For all treatment conditions, the relative GFP-GR fluorescence at the array for the averaged cells paralleled the RNA FISH measurements, suggesting that image analysis accurately detected an increase in steady-state GR association with the MMTV array that was responsible for the increase in transcriptional activity. The antagonist-dependent decreases in GR association with the MMTV promoter were confirmed by chromatin immunoprecipitation experiments, supporting the image analysis results. A pronounced cell-to-cell variability was observed in RNA FISH signal and GR-MMTV association within treatment groups. We observed a nonlinear relationship between GR-MMTV association and RNA FISH in individual cells, indicating that differences in GR-MMTV interaction account for some, but not all, of the transcriptional heterogeneity between individual cells. In selected cell subpopulations with equal levels of GR-MMTV association, there was a decrease in RNA FISH signal with RU486 treatment compared with dexamethasone treatment. These results indicate that stochastic events occurring after GR-promoter association, such as the actions of chromatin remodeling complexes or other cofactors, change in a ligand-dependent manner and regulate heterogeneous transcription in individual cells.

Animals↗
PubMed2003

Mitochondrial membrane permeabilization and superoxide production during apoptosis. A single-cell analysis.

The temporal relationship between mitochondrial membrane permeabilization and reactive oxygen species production during apoptosis remains unknown. We analyzed the rate of superoxide production of human breast carcinoma cells expressing a cytochrome c-green fluorescent protein (cyt-c-GFP) fusion protein at the single-cell level during apoptosis. In cells treated with the proapoptotic agents staurosporine (3 microm) or tumor necrosis factor-alpha (100 ng/ml), the release of cyt-c-GFP was individually set for each cell, and the majority of the fusion protein was released in less than 10 min. Prior to the release of the fusion protein, cells demonstrated a constant rate of superoxide production determined with the probe hydroethidine. After the release was completed, the superoxide concentration increased rapidly to a level more than 3-fold above baseline. Treatment with the broad spectrum caspase inhibitor z-Val-Ala-Asp(O-methyl)-fluoromethylketone (z-VAD-fmk; 200 microm) did not alter the kinetics of the cyt-c-GFP release but significantly reduced superoxide concentration after the release of cyt-c-GFP. Interestingly, treatment with z-VAD-fmk also reduced the increase in superoxide concentration in response to menadione in the absence of mitochondrial cyt-c-GFP release. Mitochondrial depolarization with the protonophore carbonyl cyanide p-trifluoromethoxy-phenylhydrazone per se did not trigger cyt-c-GFP release or an increase in superoxide production. Our data suggest that mitochondria increase their superoxide production during apoptosis directly after the quantitative release of soluble intermembrane proteins and demonstrate novel antioxidative effects of the commonly used caspase inhibitor z-VAD-fmk.

Apoptosis↗
PubMed2001

The tumor cells in nodular lymphocyte-predominant Hodgkin disease are clonally related to the large cell lymphoma occurring in the same individual. Direct demonstration by single cell analysis.

Large cell lymphoma (LCL) sometimes occurs concurrently or subsequently in patients with nodular lymphocyte-predominant Hodgkin disease (NLPHD). Although there is evidence of a clonal relationship between LCL and NLPHD, there has been no direct demonstration that the lymphocytic and histiocytic (L&H) cells in NLPHD are related to the tumor cells in LCL. We identified 2 cases of NLPHD with an associated LCL. Single L&H cells, the Reed-Sternberg cell variants in NLPHD, were isolated from immunostained tissue sections by micromanipulation, and the immunoglobulin heavy chain gene (IgH) complementarity determining region (CDR) III of the cells was amplified by the polymerase chain reaction (PCR). The products were compared with those obtained from microdissected LCL cells using polyacrylamide gel electrophoresis and nucleotide sequencing. The IgH CDRIII sequences from the L&H cells were related to each other, but also showed nucleotide substitutions, consistent with a germinal center origin. The sequences from the L&H cells also were related to those from the corresponding LCL cells. We have provided direct evidence through sequence analysis of the IgH CDRIII that the L&H cells are clonally related to the corresponding LCL arising in 2 cases of NLPHD.

Adult↗
PubMed1984

A comparison of volume growth during bud and mycelium formation in Candida albicans: a single cell analysis.

When stationary phase cells of the dimorphic yeast Candida albicans are diluted into fresh medium at pH 4.5 (low pH), they synchronously form ellipsoidal buds, but when diluted into the same medium at pH 6.7 (high pH), they synchronously form elongate mycelia. Using a perfusion chamber to monitor single cells, we have compared the rates of volume growth between budding and mycelium-forming cells. Results are presented which demonstrate that: (1) after release from stationary phase into medium of low or high pH, each original sphere grows in volume to the time of initial evagination, but does not grow subsequently; (2) successive budding on the original mother cell occurs without interruption resulting in continuous volume growth; however, an interruption in volume growth of the initial bud (B1) occurs before it in turn evaginates; and (3) the rate of volume growth of the first bud at low pH is identical to the rate of volume growth of the mycelium at high pH even though the surface to volume ratios are quite different. The last result is unexpected and is therefore considered in relation to cell wall deposition.

Candida albicans↗
PubMed2000

Quantification of self-recognition in multiple sclerosis by single-cell analysis of cytokine production.

Identifying and quantifying autoaggressive responses in multiple sclerosis (MS) has been difficult in the past due to the low frequency of autoantigen-specific T cells, the high number of putative determinants on the autoantigens, and the different cytokine signatures of the autoreactive T cells. We used single-cell resolution enzyme-linked immunospot (ELISPOT) assays to study, directly ex vivo, proteolipid protein (PLP)-specific memory cell reactivity from MS patients and controls. Overlapping 9-aa-long peptides, spanning the entire PLP molecule in single amino acid steps, were used to determine the frequency and fine specificity of PLP-specific lymphocytes as measured by their IFN-gamma and IL-5 production. MS patients (n = 22) responded to 4 times as many PLP peptides as did healthy controls (n = 22). The epitopes recognized in individual patients, up to 22 peptides, were scattered throughout the PLP molecule, showing considerable heterogeneity among MS patients. Frequency measurements showed that the number of PLP peptide-specific IFN-gamma-producing cells averaged 11 times higher in MS patients than in controls. PLP peptide-induced IL-5-producing T cells occurred in very low frequencies in both MS patients and controls. This first comprehensive assessment of the anti-PLP-Th1/Th2 response in MS shows a greatly increased Th1 effector cell mass in MS patients. Moreover, the highly IFN-gamma-polarized, IL-5-negative cytokine profile of the PLP-reactive T cells suggests that these cells are committed Th1 cells. The essential absence of uncommitted Th0 cells producing both cytokines may explain why therapeutic strategies that aim at the induction of immune deviation show little efficacy in the established disease.

Adult↗
PubMed1985

Single cell analysis of commitment in early embryogenesis.

Fate maps of amphibian embryos tell us the destination of certain areas at later stages of development. After studying Vogt's fate maps, Spemann wrote (in 1938) that "the question which at once calls for an answer is whether this pattern of presumptive primordia in the beginning gastrula is the expression of a real difference of these parts, whether they are already more or less predestined or 'determined' for their ultimate fate, or whether they are still indifferent and will not receive their determination until a later time." Until recently answers to this question have relied upon explant experiments, which indicate that by the late blastula stage ectoderm, mesoderm and endoderm regions are distinctly determined. By using a method involving single cell labelling and transplantation, it is now possible to pinpoint more accurately the time during early embryogenesis at which individual blastomeres become committed. In the vegetal pole, determination towards endoderm is a gradual process beginning during the middle blastula stage (stage 8) and completed by the beginning of gastulation (stage 10). This method offers the possibilities of comparing the committed and the uncommitted state and studying at a molecular level the mechanisms of cell determination.

Amphibians↗
PubMed2001

Single cell analysis of CAG repeat in brains of dentatorubral-pallidoluysian atrophy (DRPLA).

Somatic mosaicism of an expanded repeat is present in tissues of patients with triplet repeat diseases. Of the spinocerebellar ataxias associated with triplet repeat expansion, the most prominent heterogeneity of the expanded repeat is seen in dentatorubral-pallidoluysian atrophy (DRPLA). The common feature of this somatic mosaicism is the difference in the repeat numbers found in the cerebellum as compared to other tissues. The expanded allele in the cerebellum shows a smaller degree of expansion. We previously showed by microdissection analysis that the expanded allele in the granular layer in DRPLA cerebellum has less expansion than expanded alleles in the molecular layer and white matter. Whether this feature of lesser expansion in granule cells is common to other types of neurons is yet to be clarified. We used a newly developed excimer laser microdissection system to analyze somatic mosaicism in the brains of two patients, one with early- and another with late-onset DRPLA, and used single cell PCR to observe the cell-to-cell differences in repeat numbers. In the late onset patient, repeat expansion was more prominent in Purkinje cells than in granule cells, but less than that in the glial cells. In the early onset patient, repeat expansion in Purkinje cells was greater than in granule cells but did not differ from that in glial cells. These findings suggest that there is a difference in repeat expansion among neuronal subgroups and that the number of cell division cycles is not the only determinant of somatic mosaicism.

DNA Mutational Analysis↗
PubMed2006

Asynchronous progression through the lytic cascade and variations in intracellular viral loads revealed by high-throughput single-cell analysis of Kaposi's sarcoma-associated herpesvirus infection.

Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus-8) is frequently tumorigenic in immunocompromised patients. The average intracellular viral copy number within infected cells, however, varies markedly by tumor type. Since the KSHV-encoded latency-associated nuclear antigen (LANA) tethers viral episomes to host heterochromatin and displays a punctate pattern by fluorescence microscopy, we investigated whether accurate quantification of individual LANA dots is predictive of intracellular viral genome load. Using a novel technology that integrates single-cell imaging with flow cytometry, we found that both the number and the summed immunofluorescence of individual LANA dots are directly proportional to the amount of intracellular viral DNA. Moreover, combining viral (immediate early lytic replication and transcription activator [RTA] and late lytic K8.1) and cellular (syndecan-1) staining with image-based flow cytometry, we were also able to rapidly and simultaneously distinguish among cells supporting latent, immediate early lytic, early lytic, late lytic, and a potential fourth "delayed late" category of lytic replication. Applying image-based flow cytometry to KSHV culture models, we found that de novo infection results in highly varied levels of intracellular viral load and that lytic induction of latently infected cells likewise leads to a heterogeneous population at various stages of reactivation. These findings additionally underscore the potential advantages of studying KSHV biology with high-throughput analysis of individual cells.

Antigens, Viral↗