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At least 91 records · Page 5Linked to original sources

PubMed1991

Nitrendipine-induced inhibition of calcium influx in a human T-cell clone: role of cell depolarization.

An increase in intracellular calcium concentration stimulated by anti-CD2 or CD3 antibodies has been measured with Fura-2 in P28 cells, a human CD4+ T cell clone. This intracellular calcium increase was sensitive to membrane potential changes, being increased when the cells were hyperpolarized and decreased when they were depolarized. The intracellular calcium increase was inhibited by nitrendipine (1-50 microM). Nitrendipine also induced a depolarization of the cells, due to the blockade of a potassium conductance. The inhibition of the calcium increase caused by nitrendipine could be partially reversed by hyperpolarizing the cells with valinomycin. It is concluded that the effects of nitrendipine on potassium channels may account for a large part of the inhibition that nitrendipine exerts on the calcium increase elicited by CD2 or CD3 stimulation.

Antibodies, Monoclonal↗

PubMed2006

The maturation potential of NK cell clones toward autologous dendritic cells correlates with HMGB1 secretion.

Interaction of NK cells with autologous immature dendritic cells (iDCs) results in reciprocal activation. We have previously reported that NK cells trigger iDC to polarize and secrete IL-18; in turn, DC-activated NK cells secrete the nuclear protein/proinflammatory cytokine high mobility group box protein 1 (HMGB1), which induces DC maturation and prevents DC from lysis. However, activated NK cells can also kill iDC. To investigate whether effector and maturative properties may coexist or segregate in different NK subsets, human NK cell clones were generated and analyzed for their effects on iDC. We found that the ability of different NK cell clones to induce iDC maturation is unlinked to their phenotypic and cytolytic features but correlates with the relocation of HMGB1 from nucleus to cytoplasm. "Maturative" NK cell clones secrete HMGB1 spontaneously. It is interesting that secretion is strongly enhanced by engagement of the surface molecule NKp30 but only slightly induced by triggering of the activating NK receptor CD16. However, culturing freshly isolated NK cells for 1 week with low doses of anti-CD16 triggers the relocation of HMGB1 from nucleus to cytoplasm and its spontaneous secretion, resulting in a stronger maturation potential of the NK cells. Together, our data indicate that NK cells comprise functionally different subsets, endowed with different capacities to secrete HMGB1 and to induce maturation of autologous iDC. Nonetheless, maturation properties can be modulated by different stimuli. This suggests that depending on the environmental stimuli, NK/iDC interaction can lead to different outcomes, thus influencing immune response.

Antigens, CD↗

PubMed1985

Fine specificity analysis of human influenza-specific cloned cell lines.

Influenza-specific human-T-cell clones, proliferating in the presence of virus-infected cells with restriction by class II molecules and displaying class II-restricted CTL activity or specific helper activity in antibody synthesis, have been analyzed for antigenic specificities. All of them were obtained by in vitro stimulation against influenza A/Texas virus. In all cases the virus specificity appeared identical in cytolytic and proliferative responses. Three of the clones were broadly cross-reactive, recognizing all or almost all type A influenza strains. The three remaining clones were subtype specific when tested with human strains and recognized the surface glycoproteins of influenza virus. One of these lines reacted with an epitope of the neuraminidase N2 while the other two recognized the hemagglutinin H3. By using a large panel of mammalian and avian influenza strains, it can be demonstrated that hemagglutinin-specific human T cells can recognize a cross-reacting determinant shared by H3 and H4 subtypes of hemagglutinin which has never been detected with antibodies.

Animals↗

PubMed1991

Dengue virus-specific, human CD4+ CD8- cytotoxic T-cell clones: multiple patterns of virus cross-reactivity recognized by NS3-specific T-cell clones.

Thirteen dengue virus-specific, cytotoxic CD4+ CD8- T-cell clones were established from a donor who was infected with dengue virus type 3. These clones were examined for virus specificity and human leukocyte antigen (HLA) restriction in cytotoxic assays. Six patterns of virus specificities were determined. Two serotype-specific clones recognized only dengue virus type 3. Two dengue virus subcomplex-specific clones recognized dengue virus types 2, 3, and 4, and one subcomplex-specific clone recognized dengue virus types 1, 2, and 3. Four dengue virus serotype-cross-reactive clones recognized dengue virus types 1, 2, 3, and 4. One flavivirus-cross-reactive clone recognized dengue virus types 1, 2, 3, and 4 and West Nile virus (WNV), but did not recognize yellow fever virus (YFV), whereas three flavivirus-cross-reactive clones recognized dengue virus types 1, 2, 3, and 4, WNV, and YFV. HLA restriction in the lysis by these T-cell clones was also heterogeneous. HLA-DP, HLA-DQ, and HLA-DR were used as restriction elements by various T-cell clones. We also examined the recognition of viral nonstructural protein NS3, purified from cells infected with dengue virus type 3 or WNV, by these T-cell clones. One serotype-specific clone, two dengue virus subcomplex-specific clones, and three dengue virus serotype-cross-reactive clones recognized NS3 of dengue virus type 3. One flavivirus-cross-reactive clone recognized NS3 of dengue virus type 3 and WNV. These results indicate that heterogeneous dengue virus-specific CD4+ cytotoxic T cells are stimulated in response to infection with a dengue virus and that a nonstructural protein, NS3, contains multiple dominant T-cell epitopes.

Animals↗

PubMed1996

Human self-reactive T cell clones expressing identical T cell receptor beta chains differ in their ability to recognize a cryptic self-epitope.

Recognition of self-antigens by T lymphocytes is a central event in autoimmunity. Understanding of the molecular interactions between T cell receptors (TCR) and self-epitopes may explain how T cells escape thymic education and initiate an autoimmune reaction. We have studied five human in vivo activated T cell clones specific for the region 535-551 of human thyroid peroxidase (TPO) established from a Graves' patient. Three clones (37, 72, and 73) expressed identical TCR beta and alpha chains rearranging V beta 1.1 and V alpha 15.1, and were considered sister clones. Clone 43 differed from clone 37 and its sisters in the J alpha region only. Clone NP-7 expressed V beta 6.5 but rearranged two in-frame TCR alpha chain, both using the V alpha 22.1 segment. Fine epitope mapping using nested peptides showed that clones using identical TCR beta chains, identical V alpha, but a different J alpha recognized distinct, nonoverlapping epitopes in the TPO 535-551 region. This finding shows that a different J alpha region alone leads to a heterogeneous pattern of recognition. This indicates that the "restricted" TCR V region usage sometimes found in autoimmune diseases may not always correspond to identical epitope recognition. To confirm that clones 37 (and its sisters) and 43 recognize different epitopes, the T cell clones were stimulated with a TPO-transfected autologous Epstein-Barr virus (EBV) cell line (TPO-EBV) that presents TPO epitopes afer endogenous processing. Only clone 37 and its sisters recognizes the TPO-EBV cell line, suggesting that the epitope recognized by clone 43 is not presented upon endogenous processing. We have shown that thyroid epithelial cells (TEC), the only cells that produce TPO, express HLA class II molecules in Graves' disease and can act as an antigen-presenting cells, presenting TPO after endogenous processing to autoantigen-reactive T cell clones. We tested, therefore, whether autologous TEC induced the same pattern of stimulation as TPO-EBV; T cell clone 37 recognizes the TEC, whereas it is stimulated poorly by the TPO loaded to autologous peripheral blood mononuclear cells (PBMC). Clone 43, which fails to recognize the TPO-EBV, also fails to recognize the TEC, but is activated by exogenous TPO presented by autologous PBMC. These results show that exogenous versus endogenous processing in vivo generates a different TPO epitope repertoire, producing a "cryptic" epitope (epitope not always available for recognition). Our findings define a route by which human self-reactive T cells may escape thymic selection and become activated in vivo, thus possibly leading to autoimmunity.

Amino Acid Sequence↗

PubMed1986

Simultaneous occurrence of acute monoblastic leukemia and an abnormal B-cell clone with both cell types characterized by specific cytogenetic and immunological markers.

2 different, unrelated, abnormal clones of cells were found in a patient with acute leukemia, each clone being characterized by specific cytogenetic abnormalities and a distinct immunological phenotype. Bone marrow morphology and cytochemistry indicated an acute monoblastic leukemia, a diagnosis supported by the finding of a t(9;11) in bone marrow cells. In PHA-stimulated blood culture, another abnormal karyotype was found in 16% of the metaphases: 47,XY, + 12, inv(13), t(14;18). Immunologically, the blood contained 3 types of mononucleated cells (MNC): 1) large cells (about 70% of the MNC) with a phenotype consistent with monoblastic/monocytic leukemic cells (My7+, My8+, My906+, My4+, Leu-M3+); 2) small lymphocytic cells with either T-cell characteristics (6% of the MNC); or 3) B-cell monoclonal features (24% of the MNC). The monoclonal B-cell population was Sm kappa +, mu +, delta +, BA-1+, B1+, Y29/55+ and FMC7+. The possible origin of this abnormal (malignant) B-cell population is discussed. However, this B-cell clone was clinically silent and the patient' death precluded further observations.

Acute Disease↗

PubMed1997

Acquired cytotoxic activity of CD8+ HIV-1IIIB carrier immature T cell clones specific to CD4+CD8+ (parental) human T cell clones and normal thymocytes.

By infecting human leukemia cell lines in vitro with HIV-1IIIB' a number of HIV-1 carrier clones were generated. Among them, 5 of 13 CD8+ HIV-1 carrier T cell clones were shown to acquire a rapid cytotoxic activity (within 1 hour) specific to TdT+CD4+CD8+ immature T cells including normal thymocytes. This novel cytotoxic reaction, without requiring virus infection and indicating a rapid T cell precursor elimination during active lymphopoiesis, suggests a mechanism responsible for mature CD4+ T cell depletion in HIV-1 infected individuals.

Antigens, CD↗

PubMed1984

Activation of B cells by autoreactive T cells: cloned autoreactive T cells activate B cells by two distinct pathways.

Although the existence of autoreactive T cells has been widely reported, the functional capacities of these populations have been less well defined. Studies were therefore carried out to characterize the relationship of autoreactive T cells to antigen-specific major histocompatibility complex (MHC)-restricted T cells in their ability to act as helper cells for the induction of immunoglobulin synthesis by B cells. A number of autoreactive T cell lines and clones were isolated from antigen-primed spleen and lymph node cell populations. Autoreactive T cells were found to proliferate in response to direct recognition of syngeneic I-A or I-E subregion-encoded antigens in the absence of any apparent foreign antigen. It was shown that cloned autoreactive T cells were capable of activating B cell responses through two distinct pathways. After appropriate stimulation by syngeneic cells, autoreactive T cells polyclonally activated primed or unprimed B cells to synthesize IgM antibodies. These activated T cells functioned in these responses through an MHC-unrestricted pathway in which polyclonal responses were induced in both syngeneic and allogeneic B cells. These cloned autoreactive T cells were also able to activate IgG responses by primed B cells through a different activation pathway. In contrast to the polyclonal activation of IgM responses, the induction of IgG antibodies by the same cloned T cells required primed B cells and stimulation with the priming antigen. The activation of B cells to produce IgG was strongly MHC restricted and required the direct recognition by the autoreactive T cells of self MHC determinants expressed on the B cell surface, with no bystander activation of allogeneic B cells. These results indicate that cloned autoreactive T cells resemble antigen-specific MHC-restricted T cells in their ability to function as T helper cells through distinct MHC-restricted and MHC-unrestricted pathways.

Animals↗

PubMedDate not supplied

Early induction of anti-double-stranded DNA antibodies in lupus-prone MRL mice inoculated with Ly-24+ cells cloned from lymph node cells of an MRL/Mp-lpr/lpr mouse: possible effect of putative cytokines produced by cloned Ly-24+ cells.

We have reported that a cell line, KML1, obtained from lymph node cells of a 16-week-old female MRL/Mp-lpr/lpr (MRL/1) mouse produces a soluble factor(s) that promotes formation of anti-single-stranded (ss) DNA antibodies by cultures of spleen cells from old MRL/l mice (greater than 16 weeks old). Detailed examination revealed that KML1-7 cells cloned from the cell line KML1 were only positive for the Lys-24 (Pgp-1) phenotype, and were negative for other typical phenotypes tested, such as Thy-1, Ly-1, Ly-2, Ly-4 (L3T4) and Ly-5 (B220). This finding suggested that this line was of prothymocyte or myeloid cell lineage. From day 70 after subcutaneous inoculation of KML1-7 cells into 10-week-old MRL/Mp(-)+/+(MRL/n) mice, IgG anti-dsDNA antibodies began to replace IgM anti-dsDNA antibodies in the serum of these mice, but anticardiolipin, anti-trinitrophenyl hapten (TNP) and anti-poly(ADP-ribose) antibodies did not increase significantly. The predominant subclasses of anti-dsDNA antibodies that increased were IgG2a and IgG2b. IgG anti-dsDNA antibodies also became detectable as early as day 22 after inoculation of KML1-7 cells into MRL/l mice of 10 weeks old. The finding that in MRL/n mice the IgM isotype was increased first and was soon replaced by the IgG isotype was consistent with findings when spleen cells from MRL/n mice of 20 weeks old primed with ssDNA were cultured in the presence of conditioned medium containing a putative cytokine(s) (PC) produced by KML1-7 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Activation of a myelin basic protein-specific human T cell clone by antigen-presenting cells from rhesus monkeys.

This study addresses the capacity of peripheral blood mononuclear cells (PBMC) from rhesus monkeys (Macaca mulatta) to present myelin basic protein (MBP), a candidate auto-antigen for multiple sclerosis, to MBP-specific human CD4+ T cell clones. MHC-restriction of the human T cell clones was determined with HLA-DR-transfected L cells, and epitope specificity was established with a panel of overlapping 20-mer peptides. The MHC-DR region of the rhesus monkeys (Mamu) was characterized serologically and by sequence analysis. We identified one CD4+ HLA-DRB1*0301-restricted Th1-like human T cell clone (ES-BP8) that was activated to proliferation with human or rhesus monkey MBP, or peptide MBP 29-48 presented by PBMC from six different rhesus monkeys expressing the Mamu-DRB1*0305 or -DRB1*0306 alleles. After transformation to continuous growth with Herpesvirus saimiri, the T cell clone could still be stimulated by antigen (Ag) and Ag-presenting cells (APC) from monkeys. Two other T cell clones with the same HLA-restriction and the same peptide-specificity did not respond to MBP presented by these rhesus monkeys. The exon 2 sequences HLA-DRB1*0301, Mamu-DRB1*0305 and -DRB1*0306 differ at positions 32, 47, 67, 73 and 86. These amino acid differences are not critical for the binding of MBP 29-48 and do not abrogate recognition by the clone ES-BP8, but interfere with the recognition of the two other HLA-DRB1*0301-restricted T cell clones. In conclusion, studying Ag-presentation from rhesus monkey may provide further insight into the interaction of antigenic peptide, TCR and MHC.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗

PubMed1983

Immunocytochemical characterization of cloned cells from normal adult rat brain.

A cell clone, isolated from normal adult rat brain and maintained in culture for many passages, has been previously characterized by electron microscopy. Immunohistochemistry has now been shown that it possesses glutamine synthetase (GS) which supports its astrocytic origin. Cells failed, however, to express glial fibrillary acidic protein (GFAP) but did express the intermediate filament protein vimentin. The presence of fibronectin confirms the normal derivation of these cells and excludes the possibility of malignant transformation.

Animals↗

PubMed1991

Human B cell clones can be induced to proliferate and to switch to IgE and IgG4 synthesis by interleukin 4 and a signal provided by activated CD4+ T cell clones.

In the present study, it is demonstrated that cloned surface IgM-positive human B cells can be induced to proliferate and to switch with high frequencies to IgG4 and IgE production after a contact-mediated signal provided by T cell clones and interleukin 4 (IL-4). This T cell signal is antigen nonspecific and is provided by activated CD4+ cells, whereas activated CD8+ or resting CD4+ T cell clones are ineffective. 15-35% of the B cell clones cultured with cloned CD4+ T cells and IL-4 produced antibodies; 35-45% of those wells in which antibodies were produced contained IgE and IgG4. In addition to B cell clones that produced IgG4 or IgE only, B cell clones producing multiple isotypes were observed. Simultaneous production of IgG4 and IgE, IgM, IgE, and IgM, or IgG4 and IgE was detected, suggesting that during clonal expansion switching might occur in successive steps from IgM to IgG4 and IgE. In addition, production of only IgM, IgG4, and IgE during clonal expansion indicates that this isotype switching is directed by the way a B cell is stimulated and that it is not a stochastic process.

Antibodies, Monoclonal↗

PubMed1985

Lymphokine-activated killer (LAK) cell phenomenon. IV. Lysis by LAK cell clones of fresh human tumor cells from autologous and multiple allogeneic tumors.

Activated killer cells are generated by the incubation of peripheral blood mononuclear leukocytes (PBL) in the lymphokine interleukin 2 (IL-2). Unseparated populations of these lymphokine-activated killer (LAK) cells lyse a variety of fresh noncultured human tumor targets, but they do not kill normal PBL. This study analyzed the generation and lytic specificity of LAK cell clones. Of 49 (84%) clones isolated by limiting-dilution techniques from a whole population of LAK cells, 41 manifested significant LAK cell activity. LAK cell clones had varied cell surface phenotypes. Clones with high and intermediate LAK cell activity were Leu 2+3-4+7-DR+Tac+ and Leu 2-3+4+7-DR+Tac+, respectively. Single LAK cell clones lysed multiple fresh human tumor targets including autologous sarcoma, 5 allogeneic sarcomas, and a colon cancer in addition to the cultured cell line K562. Autologous PBL were not lysed. Tumor targets were each lysed by multiple LAK cell clones. Sixteen subclones were derived from 5 of these LAK cell clones. These subclones had 99% or greater probability of being derived from a single cell. These subclones also exhibited lysis of multiple tumor targets. These findings suggest the existence of a shared determinant, expressed by multiple human tumors, which is recognized in common by multiple LAK cell clones.

Antibodies, Monoclonal↗

PubMed1995

Effect of adriamycin on the RPC C2A cloned cell line from rat incisor pulp.

BACKGROUND AND METHODS: RPC C2A cells, cloned from Wistar rat incisor pulp, were grown in culture 2-7 days after exposure to adriamycin at a concentration of 0.1 mg/L for 2 hours. Morphological changes, labelled proline incorporation and alkaline phosphatase activity were studied in response to this treatment. RESULTS: At the light microscopic level, colonies of enlarged cells appeared 2 days after adriamycin treatment. The size of these colonies increased during the course of this study. The control samples showed no apparent changes. At the electron microscopic level, the small cells in the adriamycin-treated cultures showed fewer vesicles than the controls, but more prominent rough endoplasmic reticulum. However, the enlarged cells contained an abundance of vesicles, and few profiles of rough endoplasmic reticulum. Radiolabelled proline incorporation in the control group was significantly higher than the experimental after 2 days in culture, but showed no significant difference after 7 days. Histological staining for alkaline phosphatase showed that there was a slightly higher intensity in the control samples than in the experimental after 7 days in culture. Quantitative analysis showed that there were more alkaline phosphatase stained cells in the control than in the experimental cultures at this time. CONCLUSIONS: This study has shown that the RPC C2A cells will respond to adriamycin treatment in vitro, where the acute effects were quite different from the protracted effects with respect to labelled proline incorporation and alkaline phosphatase activity.

Alkaline Phosphatase↗

PubMed1984

Rapid expansion of allospecific cytotoxic T cell clones using nonspecific feeder cell lines without further addition of exogenous IL2.

The availability of large numbers of functionally defined cloned T cells would facilitate biochemical and molecular studies and might be a prerequisite for in vivo immunotherapy with cytotoxic lymphocytes. Exogenous interleukin-2 (IL-2) is generally considered to be the most important medium supplement for the growth of human T cells or cloned T cells. We have studied the role of particular feeder cells or stimulator cells, or both, on the expansion of a panel of cytotoxic and noncytotoxic human T cell clones. By using a combination of peripheral blood lymphocytes (PBL) and Epstein-Barr virus (EBV)-transformed B cell lines (B-LCL) as feeder cells in the presence of lectins, we were able to achieve continuous and rapid expansion of phenotypically different allospecific cytotoxic and noncytotoxic T cell clones even without (further) addition of exogenous IL-2. This culture system allows expansion of cloned cells for up to 60 generations within two months with full retention of cytolytic activity and the original target cell specificity, and without the obligatory addition of the original stimulator cell. It was found that, in principle, all combinations of EBV-transformed B cell lines (or even leukemia-derived B cell lines) and PBL feeder cells could serve the purpose, although some B cell lines gave better results than others. No evidence for HLA restriction between responder and feeder or between feeder cells was found, because cells could also be expanded with autologous feeder cells alone. The system appeared to be suitable for the expansion of various types of cytotoxic and non cytotoxic T cells, including cloned directed against major histocompatibility complex (MHC) class I or MHC class II antigens as well as MHC-nonrestricted activated killer (AK) clones.

B-Lymphocytes↗

PubMed1989

[The protein-synthesizing apparatus of a BHK-21 (C-13) cell culture and of its large-cell clone C-9].

Cell line BHK-21 (C-13) and its large cell clone C-9 differ in morphology, karyotype and cultural properties. Clone C-9 is polyploid. It has been shown that C-9 clone cells display 2.5-3-fold excess in the nucleolus organizer region (NOR) in chromosomes, and 2-3 times higher intensity of protein synthesis and of ribosomal material content compared to the original line. Data of sedimentation analysis and of protein synthesis activity of the total ribosomal material in the cell-free translational system from rabbit reticulocytes allow to conclude that the quantity and size of polyribosomes in C-9 cells are higher than in cells of the original line. Apparently, the quantity of NOR-chromosomes reflect the activity of protein translation system of investigated cells.

Animals↗

PubMed1982

Sendai virus-specific T cell clones II. Induction of interferon production by Sendai virus-specific T helper cell clones.

Interferon (IFN) was detected upon co-culture of cloned Sendai virus (SV)-specific T lymphocyte with SV-presenting syngeneic stimulator cells. The antiviral activity was defined as IFN-alpha, beta. The T cell clones, upon contact with antigen-presenting stimulator cells, stimulated adherent cells present in the stimulator cell population to secrete IFN. Induction of IFN production was independent from interleukin 2 production by the T cell clones.

Animals↗

PubMed1994

Recognition of T cell epitopes and lymphokine secretion by rye grass allergen Lolium perenne I-specific human T cell clones.

T cell lines (TCL) and CD4+ T cell clones (TCC) with specificity for the rye grass allergen Lolium perenne (Lol p) I were isolated from the blood of nine donors, six having active atopic disease, two being in remission, and one having IgE anti-Lol pI Abs but not atopic disease. The T cell epitopes of Lol pI were determined by TCLs and TCCs reactivity with 23 overlapping, 20 amino acid-long peptides spanning the entire length of the 230 amino acid-long allergen. In addition, the Th subsets (Th1, Th2, Th0, Thp) were determined by measuring IL-2, IFN-gamma, and IL-4 in the supernatants of TCC activated with Lol pI and irradiated APC. TCC from individuals from which a large panel of clones were obtained from 10(5) PBMC initial cultures recognized multiple peptides (5-9) and 23 overlapping peptides a total of 16 were recognized by at least one TCC from one of the patients. These 16 peptides were derived from all areas of the Lol pI molecule, indicating the ability of human Th cells to recognize many peptide epitopes on Lol pI. Although no clear cut immunodominant peptides were detected, T cell clones of 50% of the patients reacted with peptide 191-210. There was no correlation between peptide epitope reactivity and lymphokine secretion pattern of the TCC. Of 12 TCC obtained from six patients with active atopic disease, four (33%) were of Th1, five (42%) of Th2, one (8%) of Thp, and two (17%) of Th0 type. Of 14 TCCs isolated from three atopic donors in remission, five (36%) were of Th1, three (21%) of Th2, four (29%) of Thp, and two (14%) of Th0 type. The data demonstrate that T cells from rye grass pollen allergic patients can recognize multiple peptide epitopes on Lol pI scattered over the entire molecule. No correlation existed between epitope reactivity and lymphokine secretion pattern of the TCC.

Adolescent↗