Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cells”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed1997

Immunologic and virologic characterization of the primary infiltrating cells in the aqueous humor of human T-cell leukemia virus type-1 uveitis. Accumulation of the human T-cell leukemia virus type-1-infected cells and constitutive expression of viral and interleukin-6 messenger ribonucleic acids.

PURPOSE: To characterize immunologically and virologically the infiltrating cells in the aqueous humor of patients with human T-cell leukemia virus type-1 (HTLV-1) uveitis (HU). METHODS: With their informed consent, patients had 0.1 ml of the aqueous humor in the anterior chamber collected with a needle under an operating microscope. An aliquot of the collected sample from patients without steroid therapy was examined by May-Giemsa staining and immunocytochemically. The presence of the HTLV-1-infected cells was investigated by polymerase chain reaction (PCR) using the gag and pol regions of the provirus genome. The population of the infected cells was compared by PCR testing the amplification of the virus genome from 60 cells, or determining the endpoint of successful amplification of the twofold dilution series of the samples, collected from the aqueous humor and peripheral blood mononuclear cells (PBMCs), which were obtained at the same time. Expression of viral and cytokine genes was studied by reverse transcriptase-PCR (RT-PCR). The interleukin-6 (IL-6) level in the aqueous humor of patients with HU and control subjects was measured by a high-sensitivity enzyme-linked immunosorbent assay kit. RESULTS: The number of the infiltrating cells ranged from 475 to 3563 (mean = 2111) per 0.1 ml of aqueous humor, and all the identifiable cells were lymphocytes. Most of them were CD3-positive T cells (mean = 78%), whereas CD4-positive cells constituted less than half (mean = 35.3%). HTLV-1 provirus was detected by PCR in the infiltrating cells of 36 of 38 patients with HU tested, whereas it was detected in 1 of 4 seropositive patients with other entities of uveitis. A higher population of the infected cells in the aqueous humor than in the PBMC was found in seven of nine patients with HU by two independent approaches. Expression of HTLV-1 env or pX genes or both was shown in all 12 patients with HU tested by RT-PCR. IL-6 messenger ribonucleic acid (mRNA) was detected by RT-PCR in 10 of these 12 patients, whereas those of interleukin-1 alpha, interleukin-2, interleukin-4, and tumor-necrosis factor-alpha were not, and that of interferon-gamma was detected in only 1 patient. The IL-6 level was elevated significantly in the aqueous humor of nine patients with HU compared with that of five control subjects (520.2 +/- 841 pg/ml versus 2.77 +/- 1.59 pg/ml, P < 0.01 by Mann-Whitney test). CONCLUSIONS: HU is characterized by lymphocytic infiltration with a predominance of T cells and by the presence and probable accumulation of HTLV-1-infected lymphocytes in the affected eye. Production of viral antigens and IL-6 by the infiltrating cells could be responsible for the development of HU.

Adult↗
PubMed1983

The role of accessory cells in polyclonal T cell activation II. Induction of interleukin 2 responsiveness requires cell-cell contact.

It has previously been reported (Hünig, T. et al., Eur. J. Immunol. 1983. 13:1) that highly purified peripheral T cells do not respond to concanavalin A (Con A) even in the presence of Con A-induced spleen cell supernatant as a source of interleukin 2 (IL 2). In the present report, the hypothesis was tested whether this unresponsiveness correlates with the observed inability of Con A to mediate cell-cell contact between highly purified T cells. It was found that T cells, pretreated with neuraminidase to reduce their net negative charge, were both aggregated and rendered IL 2-reactive by Con A. In addition, leukoagglutinin (LA) was found to be able to both agglutinate untreated T cells and to make them IL 2-reactive. Neuraminidase treatment reduced the concentration of LA required to mediate both effects. Neuraminidase treatment did not alter the overall Con A-binding capacity of T cells, nor did it induce reactivity to IL 2 in the absence of lectin. Furthermore, irradiated, neuraminidase-treated T cells served as accessory cells (AC) in the induction of responsiveness to IL 2, but not for production of IL2, which depends on Ia+ AC. Finally, Lyt-2- neuraminidase-treated peripheral T cells responded in the same fashion as whole T cell populations, indicating that at least some T cells of the helper phenotype need not interact with Ia+AC for the induction of IL 2 responsiveness.

Animals↗
PubMed1995

Expression of the intercellular adhesion molecule-1 on high endothelial venules and on non-lymphoid antigen handling cells: interdigitating cells, antigen transporting cells and follicular dendritic cells.

Intercellular adhesion molecule-1 (ICAM-1) has been implicated in the development of germinal center reactions in vitro, and the present study was undertaken to determine the distribution of ICAM-1 in active germinal centers in vivo and in murine secondary lymphoid tissues in general. Anti-ICAM-1-specific monoclonal antibodies were used in conjunction with immunohistochemistry at both the light and ultrastructural levels of resolution. Examination of cryostat sections of lymph nodes, spleens, and Peyer's patches revealed that anti-ICAM-1 distinctly labeled cells in the light zones of germinal centers, a few cells in the T cell zones (e.g. paracortex of lymph nodes), cells in the sinus floor of the subcapsular sinuses of lymph nodes, and high endothelial venules (HEV). Ultrastructural studies revealed that the cells labeling with anti-ICAM-1 in germinal centers were follicular dendritic cells (FDC) which appeared to have more ICAM-1 than any other cell type. The surfaces of well-developed, intricate, convoluted FDC processes were intensely labeled even under conditions where B cells appeared negative. Interdigitating cells (IDC) were also labeled as were certain endothelial cells in the HEV. The cells in the subcapsular sinus floor labeling with anti-ICAM-1 were the "antigen transporting cells" (ATC) that carry antigen-antibody complexes into lymph node follicles. We suspect ATC are FDC precursors which mature into FDC in the follicles. Interestingly, FDC, IDC, and ATC are 3 important accessory cells known to handle antigens in specific compartments of lymphoid tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Intimal cell mass-derived atherosclerotic lesions in the abdominal aorta of hyperlipidemic swine. Part 1. Cell of origin, cell divisions and cell losses in first 90 days on diet.

Atherosclerotic lesions may originate and develop in a variety of ways. In this study we are focusing our attention on atherosclerotic lesions arising in normally occurring intimal cell masses (ICM) in the abdominal aortas of hyperlipidemic (HL) swine. Times chosen for study were 0, 14, 49 and 90 days on HL diet; mash-fed swine were used as controls. Total numbers of cells in the ICM of HL and mash swine were similar at 14 and 49 days; by 90 days the number of cells had increased dramatically in the HL swine to 8-fold greater than control values. Changes present at 49 days and thus preceding increase in cell numbers included extensive intracellular lipid accumulation with by count nearly half of the ICM cells involved and elevated tritiated thymidine labeling indices (LI) 4-fold greater than control. Differential cell counts by transmission electron microscopy were made on the ICM lesions in the HL swine at 49 and 90 days. More than 95% of all cells were smooth muscle cells (SMC), with relatively few monocytes being present. Calculations from the LI and total cell counts showed that the entire increase in cell numbers could be accounted for by divisions among the resident SMC in the ICM. Further calculations suggested that cell losses (deaths) from the ICM were minimal. Scanning electron microscopy studies reported elsewhere revealed no loss of endothelial integrity. The results suggest: (1) that the lesions arise by stimulation of the resident SMC in the ICM to hyperplastic activity, (2) that the role of monocytes in the early development of these lesions is minimal if any, (3) that in view of the intact endothelium platelets are not likely to play an important role, (4) that ICM cell death is not a major factor, (5) that the most likely candidate for the cell growth stimulatory role (? mitogen) is some component(s) of the excess lipid that accumulates in the ICM.

Animals↗
PubMed1983

Differences in inducibility of morphological differentiation of parental cells, selected variant cells and cells from spontaneous metastases of mouse neuroblastoma cells.

The in vitro sensitivities to differentiating agents of a murine neuroblastoma cell line (N18) and a selected variant cell line (N18-LM5) were examined. In addition, the sensitivities to differentiating agents of cells from spontaneous metastases produced by N18 cells were examined. When N18 cells (1 X 10(5) cells/mouse) were injected into the lateral tail vein of syngeneic A/J mice, only a few metastatic nodules formed in the liver and lung, while similar injection of N18-LM5 cells produced larger numbers of metastatic nodules. Exposure of N18 cells to differentiating agents, such as dibutyryl cyclic 3':5'-AMP (db-cAMP), prostaglandin E1, and dexamethasone, resulted in induction of differentiation in terms of neurite extension. N18-LM5 cells responded to differentiating agents to a greater extent than N18 cells, and most of the cells extended neurites when they were exposed to 1 mM db-cAMP for 3 days. On the other hand, not all cell lines from spontaneous metastases produced by N18 cells responded to db-cAMP. These results suggest that the colonizing potential of neuroblastoma cells is not necessarily correlated with loss of responsiveness to differentiating agents and that various spontaneous metastases show heterogeneity in responsiveness to differentiating agents.

Alprostadil↗
PubMed2000

Comparison of the T cell patterns in leprous and cutaneous sarcoid granulomas. Presence of Valpha24-invariant natural killer T cells in T-cell-reactive leprosy together with a highly biased T cell receptor Valpha repertoire.

The T-cell-reactive (eg, tuberculoid and reversal) forms of leprosy represent a well-defined granulomatous reaction pattern against an invading pathogen. The immune response in cutaneous sarcoidosis is a granulomatous condition that pathologically is very similar to T-cell reactive leprosy. However, it lacks a defined causative agent. In view of the role of NKT cells in murine granulomas induced by mycobacterial cell walls, we have searched for the presence of NKT cells in the cutaneous lesions of both leprosy and sarcoidosis. These cells were present in T-cell-reactive leprosy but were undetectable in cutaneous sarcoidosis. We have also studied the TCR Valpha repertoire in the two diseases. In addition to Valpha24(+) NKT cells, all patients with T-cell-reactive leprosy showed a very restricted T-cell-reactive Valpha repertoire with a strong bias toward the use of the Valpha6 and Valpha14 segments. Valpha6 and Valpha14(+) T cells were polyclonal in terms of CDR3 length and Jalpha usage. In contrast, most sarcoidosis patients showed a diverse usage of Valpha chains associated with clonal or oligoclonal expansions reminiscent of antigen-driven activation of conventional T cells. Thus the origin and perpetuation of the two kinds of granulomatous lesions appear to depend on altogether distinct T-cell recruiting mechanisms.

Adolescent↗
PubMed1994

Monoclonal B cells and restricted oligoclonal T cells in T-cell-rich B-cell lymphoma.

Immunophenotyping of lymphoma using paraffin-embedded lymphoid tissue is useful in identifying the large neoplastic B cells in T-cell-rich B-cell lymphoma (TRBL), but does not succeed in deciding clonality. We studied six cases to determine the clonal population of B and T cells of TRBL. Immunohistochemistry on frozen and paraffin-embedded material showed that the cellular population in all six cases consisted mainly of T cells; fewer than ten percent of the cells stained as B cells. However, in all cases, monoclonality of the immunoglobulin was helpful for diagnosing the B-cell neoplasia. Southern blot-yielded genetic analysis showed monoclonality of B cells in three cases, but no evidence of clonality in the T cells. Moreover, gene monoclonality has been detected in all cases examined by polymerase chain reaction, using the primers for the V and J regions of the immunoglobulin heavy chain gene. For T cells, the D and J regions of the T-cell receptor (TCR) beta chain showed the same patterns of oligoclonal bands in all cells, and the V and J regions of the TCR gamma chain showed the same bands in all. The expression of TCR V beta families was polyclonal but restricted.

Aged↗
PubMed2002

Increased susceptibility of peripheral blood mononuclear cells to equine herpes virus type 1 infection upon mitogen stimulation: a role of the cell cycle and of cell-to-cell transmission of the virus.

Equine herpesvirus-1 (EHV-1) is an important pathogen of horses, causing abortion and nervous system disorders, even in vaccinated animals. During the cell-associated viremia, EHV-1 is carried by peripheral blood mononuclear cells (PBMC), mainly lymphocytes. In vitro, monocytes are the most important fraction of PBMC in which EHV-1 replicates, however, mitogen stimulation prior to EHV-1 infection increases the percentage of infected lymphocytes. The role of the cell cycle in viral replication and the role of cluster formation in cell-to-cell transmission of the virus were examined in mitogen-stimulated PBMC. Involvement of the cell cycle was examined by stimulating PBMC with ionomycin/phorbol dibutyrate (IONO/PDB) during 0, 12, 24 and 36 h prior to inoculation. Cell cycle distribution at the moment of inoculation and the percentage of EHV-1 antigen-positive PBMC at 0, 12 and 24 hours post inoculation (hpi) were determined by flow cytometry and immunofluorescence microscopy, respectively. The role of clusters was examined by immunofluorescence staining within clusters of stimulated PBMC using antibodies against EHV-1. Significant correlations were found between the increase of cells in the S- or G2/M-phase after a certain time interval of prestimulation and the increase of EHV-1 antigen-positive cells. The percentage of clusters with adjacent infected cells significantly increased from 3.3% at 8 hpi to 23.7% at 24 hpi and the maximal number of adjacent infected cells increased from 2 to 7. Addition of anti-EHV-1 hyperimmune serum did not significantly alter these percentages. Mitogen stimulation favours EHV-1 infection in PBMC by: (i) initiating cell proliferation and (ii) inducing formation of clusters, thereby facilitating direct cell-associated transmission of virus.

Animals↗
PubMed1993

Crosstalk between alpha/beta T cells and gamma/delta T cells in vivo: activation of alpha/beta T-cell responses after gamma/delta T-cell modulation with the monoclonal antibody GL3.

Although gamma/delta T cells express numerous in vitro functions similar to alpha/beta T cells, little is known about their biological functioning in vivo. Furthermore, it is unclear whether alpha/beta T cells and gamma/delta T cells act independently or in a coordinated way. In the present study, gamma/delta T cells were modulated in vivo by i.p. injection of the anti-gamma/delta T-cell receptor (TCR) monoclonal antibody GL3. GL3 administration caused disappearance of the gamma/delta TCR in spleen and lymph node cells and the gamma/delta TCR was reexpressed after in vitro cultivation for a few days. When cultured in vitro for 4 days, in the absence of foreign antigens, spleen and lymph node alpha/beta T cells from GL3-modulated mice showed vigorous proliferative responses. CD4 T lymphocytes from GL3-modulated mice produced interleukin 2, and CD8 T cells developed into cytolytic T lymphocytes in vitro capable of lysing syngeneic and allogeneic targets. Treatment with heat-inactivated GL3 or with normal hamster immunoglobulin did not cause any of these effects. These findings suggest that the anti-gamma/delta TCR monoclonal antibody GL3 modulates gamma/delta T cells in vivo and that this modulation has profound effects on alpha/beta T-cell reactivity. Hence, the data suggest a role for gamma/delta T cells in the regulation of alpha/beta T-cell activation in vivo.

Animals↗
PubMed1990

The role of integrins alpha 2 beta 1 and alpha 3 beta 1 in cell-cell and cell-substrate adhesion of human epidermal cells.

We have examined cultures of neonatal human foreskin keratinocytes (HFKs) to determine the ligands and functions of integrins alpha 2 beta 1, and alpha 3 beta 1 in normal epidermal stratification and adhesion to the basement membrane zone (BMZ) in skin. We used three assay systems, HFK adhesion to purified extracellular matrix (ECM) ligands and endogenous secreted ECM, localization of integrins in focal adhesions (FAs), and inhibition of HFK adhesion with mAbs to conclude: (a) A new anti-alpha 3 beta 1 mAb, P1F2, localized alpha 3 beta 1 in FAs on purified laminin greater than fibronectin/collagen, indicating that laminin was the best exogeneous ligand for alpha 3 beta 1. However, in long term culture, alpha 3 beta 1 preferentially codistributed in and around FAs with secreted laminin-containing ECM, in preference to exogenous laminin. Anti-alpha 3 beta 1, mAb P1B5, detached prolonged cultures of HFKs from culture plates or from partially purified HFK ECM indicating that interaction of alpha 3 beta 1 with the secreted laminin-containing ECM was primarily responsible for HFK adhesion in long term culture. (b) In FA assays, alpha 2 beta 1 localized in FAs conincident with initial HFK adhesion to exogenous collagen, but not laminin or fibronectin. However, in inhibition assays, anti-alpha 2 beta 1 inhibited initial HFK adhesion to both laminin and collagen. Thus, alpha 2 beta 1 contributes to initial HFK adhesion to laminin but alpha 3 beta 1 is primarily responsible for long-term HFK adhesion to secreted laminin-containing ECM. (c) Serum or Ca2(+)-induced aggregation of HFKs resulted in relocation of alpha 2 beta 1 and alpha 3 beta 1 from FAs to cell-cell contacts. Further, cell-cell adhesion was inhibited by anti-alpha 3 beta 1 (P1B5) and a new anti-beta 1 mAb (P4C10). Thus, interaction of alpha 3 beta 1 with either ECM or membrane coreceptors at cell-cell contacts may facilitate Ca2(+)-induced HFK aggregation. (d) It is suggested that interaction of alpha 3 beta 1 with a secreted, laminin-containing ECM in cultured HFKs, duplicates the role of alpha 3 beta 1 in basal cell adhesion to the BMZ in skin. Further, relocation of alpha 2 beta 1 and alpha 3 beta 1 to cell-cell contacts may result in detachment of cells from the BMZ and increased cell-cell adhesion in the suprabasal cells contributing to stratification of the skin.

Antibodies↗
PubMed1993

Protease inhibitors selectively block T cell receptor-triggered programmed cell death in a murine T cell hybridoma and activated peripheral T cells.

The hypothesis that cytoplasmic proteases play a functional role in programmed cell death was tested by examining the effect of protease inhibitors on the T cell receptor-mediated death of the 2B4 murine T cell hybridoma and activated T cells. The cysteine protease inhibitors trans-epoxysuccininyl-L-leucylamido-(4-guanidino) butane (E-64) and leupeptin, the calpain selective inhibitor acetyl-leucyl-leucyl-normethional, and the serine protease inhibitors diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride, all showed dose-dependent blocking of the 2B4 death response triggered by the T cell receptor complex and by anti-Thy-1. These protease inhibitors enhanced rather than inhibited IL-2 secretion triggered by T cell receptor cross-linking, showing that they did not act by preventing signal transduction. Growth inhibition induced by cross-linking the 2B4 T cell receptor, measured by inhibition of thymidine incorporation, was not generally blocked by these protease inhibitors. All five of these protease inhibitors enhanced rather than blocked 2B4 cell death triggered by dexamethasone, an agent previously shown to have a death pathway antagonistic with that of the TCR. 2B4 cytolysis by the cytotoxic agents staphylococcal alpha-toxin and dodecyl imidazole, and that caused by hypotonic conditions, was not significantly affected by the five protease inhibitors tested. The selected protease inhibitors blocked both the apoptotic nuclear morphology changes and DNA fragmentation induced by T cell receptor cross-linking, and enhanced both these properties induced by dexamethasone in 2B4 cells. The T cell receptor-induced death of activated murine lymph node T cells and human peripheral blood CD4+ T cells was blocked by both cysteine and serine protease inhibitors, showing that the protease-dependent death pathway also operates in these systems.

Animals↗
PubMed2001

Tumor cell "dead or alive": caspase and survivin regulate cell death, cell cycle and cell survival.

Cell death and cell cycle progression are two sides of the same coin, and these two different phenomenons are regulated moderately to maintain the cellular homeostasis. Tumor is one of the disease states produced as a result of the disintegrated regulation and is characterized as cells showing an irreversible progression of cell cycle and a resistance to cell death signaling. Several investigations have been performed for the understanding of cell death or cell cycle, and cell death research has remarkably progressed in these 10 years. Caspase is a nomenclature referring to ICE/CED-3 cysteine proteinase family and plays a central role during cell death. Recently, several investigations raised some possible hypotheses that caspase is also involved in cell cycle regulation. In this issue, therefore, we review the molecular basis of cell death and cell cycle regulated by caspase in tumor, especially hepatocellular carcinoma cells.

Animals↗
PubMed1983

A comparison of cell killing by heat and/or X rays in Chinese hamster V79 cells, Friend erythroleukemia mouse cells, and human thymocyte MOLT-4 cells.

The radiation and/or heat sensitivity of Chinese hamster V79 cells, Friend erythroleukemia (FELC) mouse cells, and MOLT-4 human transformed thymocytes were compared. MOLT-4 cells were more radiosensitive (D0 = 0.50 Gy) than FELC (D0 = 0.65 Gy) and V79 cells (D0 = 1.43 Gy). Arrhenius analysis showed that MOLT-4 cells were more heat sensitive than FELC or V79 cells below 42.0 degrees C, but more heat resistant at higher temperatures. In addition, the MOLT-4 cells showed a single-heat inactivation energy between 41.0 and 45.0 degrees C, while FELC and V79 cells both showed a transition in the inactivation energy at about 43.0 and 43.5 degrees C, respectively. These differences may be related to the fact that the upper temperature limit for the development of thermal tolerance during continuous heating was lower for MOLT-4 cells than for FELC or V79 cells. Killing of FELC and V79 cells was dependent on the sequence in which heat and X rays were applied, but the greatest effect was obtained when both treatments were given simultaneously. Recovery occurred when treatments were separated by incubation at 37.0 degrees C. The MOLT-4 cells did not show a sequence dependence for heating and irradiation. Survival of MOLT-4 cells after heating and/or irradiation was compared using trypan blue dye exclusion or colony formation. Both assays showed similar qualitative responses, but survival levels measured by the trypan blue assay were much higher than those determined from the colony-forming assay.

Animals↗
PubMed1996

In vitro differentiation of CD34+ hematopoietic progenitor cells toward distinct dendritic cell subsets of the birbeck granule and MIIC-positive Langerhans cell and the interdigitating dendritic cell type.

We have demonstrated recently that Birbeck granule-positive Langerhans cells (LC) can be derived from CD34+ peripheral blood progenitor cells in the presence of a seven-cytokine cocktail (CC7-7). Here, we show that the sequential use of early-acting hematopoietic growth factors, stem cell factor, interleukin (IL)-3, and IL-6, followed on day 8 by differentiation in the two-factor combination IL-4 plus granulocytemacrophage colony-stimulating factor (GM-CSF) (CC4GM) is more efficient and allows the cells to be arrested in the LC stage for more than 1 week while continuous maturation occurs in CC7-7. Maturation of LC to interdigitating dendritic cells (DC) could specifically be induced within 60 hours by addition of tumor necrosis factor-alpha (20 ng/mL) or lipopolysaccharide (100 ng/mL). Using LC that had been enriched to greater than 90% CD1a+ cells by an immunoaffinity column, we were able to define clear-cut differences between LC and DC that corroborate data of the respective cells derived from epithelial borders (LC) or from lymph nodes (LN) and spleen (DC). Thus, molecules and functions involved in antigen (AG) uptake and processing were highly expressed in LC, while those involved in AG presentation were at maximum in DC. LC were CD1a+2 DR+2, CD23+, CD36+, CD80-, CD86-, and CD25-, while DC were CD1a+/- DR+3, CD23-, CD36-, CD80+, CD86+2, and CD25+, CD40 and CD32 were moderately expressed and nearly unchanged on maturation, in contrast to monocyte-derived DC. Macropinocytosis of fluorescein isothiocyanate-dextran was dominant in LC, as were multilamellar major histocompatibility complex (MHC) class II compartments (MIICs), which were detected by electron microscopy. The functional dichotomy of these cell types was finally supported by testing the AG-presenting cell function for tetanus toxoid to primed autologous T-cell lines, which was optimal when cells were loaded with AG as LC and subsequently induced to become DC.

Antigen Presentation↗
PubMed1996

NK 1+ CD4- CD8- alphabeta T cells in the peritoneal cavity: specific T cell receptor-mediated cytotoxicity and selective IFN-gamma production against B cell leukemia and myeloma cells.

NK1+ double negative (DN) alphabeta T cells were present in the peritoneal exudate cells (PEC) of both normal and athymic B6 mice, accounting for as much as 25% of the total T cells, while their numbers were far less in the PEC of BALB/c and (BALB/c x B6)F1 mice. IL-2-dependent clones established from the DN alphabeta T cell population in the PEC of IL-2 receptor alpha-chain transgenic B6 mice exhibited potent cytotoxicity against a series of B cell lineage leukemias and myelomas, such as CD5+BCL1 and MOPC, without affecting NK-susceptible targets. The cytotoxicity of the clones against BCL1 and MOPC was specifically inhibited by anti-CD3, anti-alphabetaTCR, or anti-relevant Vbeta (Vbeta8) Ab, but not by control Abs, indicating that it was mediated by the specific alphabetaTCR/CD3. Other BALB/c-derived target cells expressing both MHC class I and class II were not affected, and neither Ab against them affected the cytotoxicity, strongly suggesting that the cytotoxicity of NK1+ DN alphabeta T cell clones was independent of the particular MHC Ags. The clones produced IFN-gamma, but little IL-2 or IL-4, in response to anti-CD3 stimulation, to the susceptible, but not resistant, targets, and to IL-12. The clones exhibited TCRalpha (Valpha8) distinct from an invariant TCRalpha (Valpha14) reported to dominate in thymic NK1+ alphabeta T cells. The presence of DN alphabeta T cells with similar functional features in the normal PEC was confirmed by the short term stimulation in vitro. The present results along with other recent reports strongly suggested that, like the mainstream alphabeta T cells, the NK1+ DN alphabeta T cell population consisted of functionally heterogeneous subsets.

Amino Acid Sequence↗
PubMed1990

Autoreactive T cells in normal mice: unrestricted recognition of self peptides on dendritic cell I-A molecules by CD4-CD8- T cell receptor alpha/beta+ T cell clones expressing V beta 8.1 gene segments.

CD4-CD8- double-negative (DN) and CD4+CD8- T cell clones were derived from splenic precursors resistant to killing by anti-Thy-1, -CD5, -CD4 and -CD8 monoclonal antibodies and complement. Both DN and CD4+ clones express functional T cell receptor (TcR) alpha/beta and exhibit strong autoreactivity in vitro. DN cells can be induced to proliferate by dendritic cells (DC) of all haplotypes tested, although this activation is inhibited by antibodies specific for I-A determinants expressed on the stimulatory DC. In contrast, CD4+ clones only respond to syngeneic or I-Ad-compatible DC. Both DN and CD4+ autoreactive clones do not proliferate when cultured with class II+ H-2d normal or tumor macrophages and B cell lines or with class II-transfected L cells, suggesting that these cells recognize self peptides only present on the surface of DC. Despite their phenotype resembling that of immature thymocytes and their inability to interact directly with B lymphocytes, DN cloned T cells, like CD4+ T cells, exhibit nonspecific helper functions and can induce polyclonal B cell proliferation and differentiation. DN TcR alpha/beta+ peripheral T cells represent, like TcR gamma/delta+ lymphocytes, a new T cell subset physiological role whose remains to be defined.

Animals↗
PubMed1993

Human T cell autoimmunity against myelin basic protein: CD4+ cells recognizing epitopes of the T cell receptor beta chain from a myelin basic protein-specific T cell clone.

We have investigated whether the normal immune system contains T cells that are able to recognize T cell receptor (TcR) determinants of autologous autoantigen-specific T cells. The T cell clone HW.BP3, specific for myelin basic protein (MBP) was isolated from a healthy donor. HW.BP3 is restricted by HLA-DR2a, and reacts to human MBP 139-153. The expressed alpha beta TcR genes of HW.BP3 were cloned and sequenced, and the sequences analyzed for potential T cell epitopes. Two synthetic peptides, one from the VDJ beta junctional (beta 1) and one from the V beta region (beta 2) of the TcR of HW.BP3, were used to select four TcR peptide-specific T cell lines from the donor of HW.BP3. All anti-TcR lines had the phenotype CD3+/CD4+/HLA-DR+/CD25+/CD45RO+, and recognized the antigen in the context of HLA-DR. Three anti-TcR lines, which had been selected for reactivity to peptide beta 1, recognized exclusively this peptide restricted by HLA-DR2b. One anti-TcR line, selected for peptide beta 2, responded to both peptides beta 1 and beta 2 when presented by autologous blood mononuclear cells, but not by HLA-DR2a- or HLA-DR2b-transfected L cells. All TcR peptide-specific T cell lines were efficiently cytotoxic. They specifically lysed autologous macrophages or HW.BP3 line cells in the presence of exogenous peptide antigen. In contrast, HW.BP3 did not present endogenous TcR peptides to the anti-TcR lines. The results demonstrate that the normal human immune system contains not only autoantigen-specific T cells, but also T cells that recognize antigenic determinants of autologous autoreactive TcR.

Amino Acid Sequence↗
PubMed1995

T cell--vascular smooth muscle cell interactions: antigen-specific activation and cell cycle blockade of T helper clones by cloned vascular smooth muscle cells.

Histological observations have demonstrated the presence of T lymphocytes in atherosclerotic plaques, often in close association with vascular smooth muscle cells (VSMC). We have examined the interaction occurring between cloned murine VSMC and histocompatibility-matched, antigen-specific Th1 and Th2 cell lines. Incubation of either Th1 or Th2 cells with antigen-pulsed VSMC resulted in the formation of T cell-VSMC conjugates accompanied by morphological changes in both cell types. This interaction resulted in an antigen-dependent activation of IL-2 receptor expression by the Th cells, demonstrating the ability of cloned VSMC to process and present antigen through the exogenous pathway. However, although the T cells were activated to express IL-2 receptors by antigen-pulsed VSMC, they were unable to progress through cell cycle. The secretion of an inhibitory mediator by VSMC was suggested by the observations that (1) fixation of the VSMC's eliminated the inhibitory signal and (2) the supernatants of IFN gamma-primed VSMC displayed similar inhibitory activity. The inhibitory effect could not be abrogated with indomethacin or an inhibitor of the generation of reactive nitrogen intermediates, indicating that prostaglandin synthesis and/or nitric oxide production are not solely responsible for the inhibition of proliferation. Flow cytometric cell cycle analysis revealed that VSMC delivered signals resulting in a late G1 blockade of T cell cycle progression. Mitogen responses of purified primary T cells are also dramatically inhibited by IFN gamma-treated VSMC, despite significant IL-2 production. Our data depict a complex and intimate T cell-VSMC interaction and suggest that mutual activation events may occur.

Animals↗