Biomedical subjects

T Kambayashi

Publications and source records attributed to T Kambayashi.

At least 19 recordsLinked to original sources

PubMed2001

Cutting edge: Regulation of CD8(+) T cell proliferation by 2B4/CD48 interactions.

The biological function of 2B4, a CD48-binding molecule expressed on T cells with an activation/memory phenotype, is not clear. In this report, we demonstrate that proliferation of CD8(+) T cells is regulated by 2B4. Proliferative responses of CD8(+) T cells were significantly reduced by anti-2B4 Ab. The effects were not potentiated by anti-CD48 Ab, suggesting that the observed responses were driven by 2B4/CD48 interactions. Surprisingly, the 2B4/CD48-dependent proliferative responses were also observed in the absence of APCs. This suggests that 2B4/CD48 interactions can occur directly between T cells. Furthermore, when activated 2B4(+)CD8(+) T cells were mixed with 2B4(-)CD8(+) TCR-transgenic T cells and specific peptide-loaded APC, the proliferation of the latter T cells was inhibited by anti-2B4 Ab. Taken together, this suggests that 2B4 on activated/memory T cells serves as a ligand for CD48, and by its ability to interact with CD48 provides costimulatory-like function for neighboring T cells.

Animals↗

PubMed2001

Soluble MHC class I molecules induce cellular death in a CD8+ T-cell hybridoma tumor model.

T cells undergo activation-induced cell death (AICD) after T-cell receptor cross-linking in the absence of co-stimulation. In this study, we examined whether AICD induced by purified MHC class I molecules could be used to selectively eliminate tumor cells in T-cell malignancies. As a model, soluble H-2K(b) molecules refolded with the chicken ovalbumin SIINFEKL peptide (K(b)-OVA) and a CD8+ T-cell hybridoma (CD8-OVA) specific for this peptide were used. Addition of CD8-OVA hybridoma cells to plastic plates adsorbed with K(b)-OVA molecules resulted in a concentration-dependent decrease in cellular proliferation. Exogenous IL-4 further depressed the proliferation of CD8-OVA cells in a dose-dependent manner in the presence, but not in the absence, of K(b)-OVA. Staining of these cells with propidium iodide confirmed that the decrease in cellular proliferation was due to apoptosis. The cytotoxic effect of plastic-immobilized K(b)-OVA could be mimicked by soluble K(b)-OVA tetramers. Furthermore, co-injection of K(b)-OVA tetramers and CD8-OVA cells into mice suppressed the tumorigenicity of CD8-OVA cells. In conclusion, we describe a system whereby soluble MHC class I molecules can be used to selectively induce cellular death in a monoclonal T-cell tumor model. With future development, the use of MHC molecules may help to eliminate specific T cells in cases of T-cell malignancy and auto-immunity.

Animals↗

PubMed2001

Purified MHC class I molecules inhibit activated NK cells in a cell-free system in vitro.

Natural killer cells have been shown to interact with MHC class I molecules via inhibitory receptors. However, it is not known whether the inhibition induced by MHC class I molecules requires other NK cell-target cell interactions. Thus, we examined whether purified MHC class I molecules alone were able to inhibit NK cell function. Purified H-2K(b) and H-2D(b) molecules inhibited the release of IFN-gamma from spleen (H-2(b))-derived lymphokine-activated killer (LAK) cell cultures stimulated by anti-NK1.1 antibody in a concentration-dependent manner. LAK cells generated from newborn mice that express low levels of MHC class I binding Ly49 inhibitory receptors were significantly less sensitive to inhibition by H-2K(b) compared to LAK cells from adult mice. Furthermore, LAK cells generated from spleen cells of Ly49C-transgenic mice were significantly more sensitive to inhibition by H-2K(b) compared to non-transgenic littermates. Taken together, the data indicate that MHC class I induced inhibition of NK cell mediated effector functions, as assessed by IFN-gamma release after NK1.1 triggering, does not require additional cell surface molecules other than MHC class I.

Animals↗

PubMed2001

Expression of the DX5 antigen on CD8+ T cells is associated with activation and subsequent cell death or memory during influenza virus infection.

The antigen recognized by the DX5 antibody (DX5 antigen) is expressed on all murine NK cells. In the present study we found that a proportion of CD8+ T cells (approximately 5%) also express the DX5 antigen in uninfected mice, and that numbers of CD8+ T cells expressing DX5 are significantly higher in the lungs of influenza virus-infected mice representing up to 50% of all CD8+ T cells on day 10 post infection. The expression of the DX5 antigen on CD8+ T cells was associated with a memory phenotype in uninfected C57BL/6 mice and with an activation phenotype during influenza virus infection. Interestingly, when lymphocytes were isolated from lungs of influenza virus-infected mice on day 10 post infection and adoptively transferred into recombination activating gene-1 (RAG1)-deficient mice, CD8+DX5+ cells could not be recovered from the recipient mice 2 days later. Moreover, CD8+DX5+ cells were not detected when lung cells were removed from day 10 influenza virus-infected mice and cultured in vitro for 2 days. However, CD8+DX5+ cells could be detected when apoptosis inhibitors were added to these cultures, suggesting that the CD8+DX5+ cells underwent apoptosis during cell culture. Furthermore, almost all DX5 expressing CD8+ cells from lungs of mice on day 10 post influenza virus infection stained positively with Annexin-V. Taken together, the data suggest that CD8+ T cells expressing DX5 are associated with an activation/memory phenotype and are biased towards apoptosis.

Adoptive Transfer↗

PubMed2001

IL-2 down-regulates the expression of TCR and TCR-associated surface molecules on CD8(+) T cells.

CD8(+) T cells are known to down-regulate the TCR complex upon ligation with its cognate MHC class I-peptide complex. In the present report, we demonstrate that stimulation of CD8(+) T cells with cytokines also leads to down-regulation of the TCR complex and TCR-associated surface molecules. A significant reduction of TCRalpha beta, CD3, CD8alpha and CD8beta surface expression was observed when CD8(+) T cells were cultured in IL-2 and to a lesser extent in IL-4 or IL-15. The down-regulation was apparent after 2 days of culture and was observed at IL-2 concentrations as low as 10 U/ml. Using TCR transgenic mice, we found that the down-regulation was associated with a decreased affinity of CD8(+) T cells to MHC class I-peptide complexes, as determined by MHC class I tetramer staining. Furthermore, the antigen-specific proliferation of IL-2-pre-activated CD8(+) T cells was significantly reduced compared to naive CD8(+) T cells or to CD8(+) T cells previously stimulated with peptide-pulsed dendritic cells. Moreover, only CD8alpha(high) but not CD8alpha(low) cells sorted from IL-2-activated CD8(+) T cells proliferated in response to specific antigen, although both subsets proliferated equally well to IL-2. Taken together, these data suggest that the down-regulation of TCR components and a subsequent decrease in affinity towards MHC class I-peptide complexes may be a mechanism by which TCR-dependent proliferation of non-specifically activated CD8(+) T cells is avoided.

Animals↗

PubMed2001

Recombinant Semliki Forest virus vaccine vectors: the route of injection determines the localization of vector RNA and subsequent T cell response.

Vectors based on Semliki Forest virus (SFV) have been widely used in vitro and in vivo to express heterologous genes in animal cells. In particular, the ability of recombinant SFV (rSFV) to elicit specific, protective immune responses in animal models suggests that rSFV may be used as a vaccine vehicle. In this study, we examined the distribution of rSFV in vivo by immunohistochemistry and RT-PCR after intravenous, intramuscular and subcutaneous injection of rSFV particles and related this to the degree of cytotoxic T lymphocyte (CTL) responses and frequency of specific T cells detected by MHC-I tetramers. We found that after i.v. injection, rSFV-RNA was distributed to a variety of different tissues, whereas it was confined locally after i.m. and s.c. injections. The persistence of the rSFV vector was transient, and no viral RNA could be detected 10 days after inoculation. All tested routes of immunization generated significant levels of antigen-specific CTL responses and increased numbers of specific CD8+ T cells, as detected by tetramer binding. The distribution of antigen-specific CTLs correlated with the in vivo distribution pattern of rSFV, with a highest frequency in the spleen or local lymph node, depending on the injection route.

Animals↗

PubMed2001

cAMP-elevating agents suppress dendritic cell function.

The administration of cAMP-elevating agents affects a number of autoimmune and inflammatory conditions. Because dendritic cells (DCs) play a pivotal role in autoimmunity and inflammation, the isolated effects of cAMP-elevating agents on the function of DCs was examined. In a dose-dependent manner, 8-Bromo cAMP, prostaglandin E(2), and 3-isobutyl-1-methylxanthine inhibited tumor necrosis factor alpha release and suppressed antigen presentation by DCs. The same effect was observed with rolipram, a specific inhibitor of phosphodiesterase type 4, but not with inhibitors of other phosphodiesterases. The decreased antigen presentation by DCs was associated with an enhanced production of interleukin (IL)-10 and with lower major histocompatibility complex type II (MHC II) expression. Furthermore, the inhibition of antigen presentation and MHC II expression was significantly reversed by treatment of DCs with neutralizing antibody against IL-10, suggesting the involvement of an IL-10-dependent mechanism. Taken together, these results might explain why certain cAMP-elevating agents such as rolipram are effective in blocking autoimmunity and inflammation.

1-Methyl-3-isobutylxanthine↗

PubMed2000

Emergence of CD8+ T cells expressing NK cell receptors in influenza A virus-infected mice.

Both innate and adaptive immune responses play an important role in the recovery of the host from viral infections. In the present report, a subset of cells coexpressing CD8 and NKR-P1C (NK1.1) was found in the lungs of mice infected with influenza A virus. These cells were detected at low numbers in the lungs of uninfected mice, but represented up to 10% of the total CD8(+) T cell population at day 10 postinfection. Almost all of the CD8(+)NK1.1(+) cells were CD8alphabeta(+)CD3(+)TCRalphabeta(+) and a proportion of these cells also expressed the NK cell-associated Ly49 receptors. Interestingly, up to 30% of these cells were virus-specific T cells as determined by MHC class I tetramer staining and by intracellular staining of IFN-gamma after viral peptide stimulation. Moreover, these cells were distinct from conventional NKT cells as they were also found at increased numbers in influenza-infected CD1(-/-) mice. These results demonstrate that a significant proportion of CD8(+) T cells acquire NK1.1 and other NK cell-associated molecules, and suggests that these receptors may possibly regulate CD8(+) T cell effector functions during viral infection.

Animals↗

PubMed2000

CD8+ T cells rapidly acquire NK1.1 and NK cell-associated molecules upon stimulation in vitro and in vivo.

NKT cells express both NK cell-associated markers and TCR. Classically, these NK1.1+TCRalphabeta+ cells have been described as being either CD4+CD8- or CD4-CD8-. Most NKT cells interact with the nonclassical MHC class I molecule CD1 through a largely invariant Valpha14-Jalpha281 TCR chain in conjunction with either a Vbeta2, -7, or -8 TCR chain. In the present study, we describe the presence of significant numbers of NK1.1+TCRalphabeta+ cells within lymphokine-activated killer cell cultures from wild-type C57BL/6, CD1d1-/-, and Jalpha281-/- mice that lack classical NKT cells. Unlike classical NKT cells, 50-60% of these NK1.1+TCRalphabeta+ cells express CD8 and have a diverse TCR Vbeta repertoire. Purified NK1.1-CD8alpha+ T cells from the spleens of B6 mice, upon stimulation with IL-2, IL-4, or IL-15 in vitro, rapidly acquire surface expression of NK1.1. Many NK1.1+CD8+ T cells had also acquired expression of Ly-49 receptors and other NK cell-associated molecules. The acquisition of NK1.1 expression on CD8+ T cells was a particular property of the IL-2Rbeta+ subpopulation of the CD8+ T cells. Efficient NK1.1 expression on CD8+ T cells required Lck but not Fyn. The induction of NK1.1 on CD8+ T cells was not just an in vitro phenomenon as we observed a 5-fold increase of NK1.1+CD8+ T cells in the lungs of influenza virus-infected mice. These data suggest that CD8+ T cells can acquire NK1.1 and other NK cell-associated molecules upon appropriate stimulation in vitro and in vivo.

Animals↗

PubMed2000

Abolished angiogenicity and tumorigenicity of Burkitt lymphoma by interleukin-10.

Because of its immunosuppressive properties, interleukin-10 (IL-10) is thought to play an important role in a number of human disease states, including inflammation, autoimmunity, and transplant rejection. In this study, we demonstrate that introduction of human or viral IL-10 genes into Burkitt's lymphoma cells markedly reduced their ability to grow as subcutaneous (sc) tumors in SCID mice. In vivo assays for angiogenesis revealed an inhibition of the angiogenic capacity of the IL-10-transfected lines. Recombinant human IL-10 abolished and viral IL-10 reduced vascular endothelial growth factor (VEGF)-165-induced neovascularization. Furthermore, IL-10 blocked the VEGF- and fibroblast growth factor (FGF)-2-induced proliferation of microvascular endothelial cells in vitro. The current observations suggest a direct role for IL-10 in the prevention of angiogenesis in human lymphoid malignancies.

Animals↗

PubMed2000

Neutrophils augment the release of TNFalpha from LPS-stimulated macrophages via hydrogen peroxide.

We examined the effect of polymorphonuclear cells on the release of tumor necrosis factor (TNFalpha) in endotoxin-treated macrophages. Human peripheral blood neutrophils were co-cultured with mouse peritoneal macrophages stimulated with lipopolysaccharide (LPS). In a dose-dependent manner, FMLP (n-formyl-methionyl-leucyl-phenylalanine) augmented the release of TNFalpha by LPS-stimulated macrophages in the presence, but not in the absence, of neutrophils. The stimulating effect of neutrophils on macrophages was reversed by catalase, suggesting that the release of hydrogen peroxide from neutrophils was responsible for augmenting macrophage TNFalpha. Moreover, the direct addition of hydrogen peroxide to macrophages resulted in an increased secretion of TNFalpha. In addition, insertion of a porous membrane between the neutrophils and macrophages cancelled the effect, indicating that adherence of neutrophils may be necessary for augmentation of TNFalpha release. In summary, the data suggest that hydrogen peroxide released from stimulated neutrophils may act as an activator of macrophage function by increasing their release of TNFalpha.

Animals↗

PubMed2000

Complicating risk factors for pyelonephritis after extracorporeal shock wave lithotripsy.

PURPOSE: The score to predict the risk of post-extracorporeal shock wave lithotripsy (ESWL) pyelonephritis was evaluated. The score was based on the multivariate analysis of risk factors available pre-operatively. Stone size, pyuria, bacteriuria, previous pyelonephritis and other adjunctive procedures had been selected and scored. METHODS: Three-hundred and forty-eight adult patients without active urinary infection undergoing ESWL therapy were studied. One of three regimens were selected by either doctor or patient: (i) no antimicrobial treatment; (ii) one dose of levofloxacin; or (iii) 1 week course of levofloxacin. Who and why selected it were described. Post-ESWL fever over 38 degrees C was defined as the unfavorable event. RESULTS/CONCLUSION: With increasing score, doctors recommend taking an antimicrobial. There were 11 bacteriuric patients and post-ESWL pyelonephritis developed in one of them. Bacteria within the stone and post-ESWL ureteral obstruction caused by the stone fragments were considered to be important in developing pyelonephritis. However, multiple factors were related with it. Although their decision was not based simply on the score, the score was confirmed to be useful in identifying the high-risk patients and, therefore, to implement cost-effective antimicrobial use.

Adolescent↗

PubMed1997

The immunomodulator AS-101 inhibits IL-10 release and augments TNF alpha and IL-1 alpha release by mouse and human mononuclear phagocytes.

AS-101 is a tellurium-based compound with known immunomodulating properties. The ability of AS-101 to potentiate the effects of chemotherapeutic drugs and augment cytokine production in vivo has led to clinical trials on AS-101 which are currently being carried out in cancer patients. In the present study we show that AS-101 selectively augments the release of TNF alpha and IL-1 alpha and inhibits the release of IL-10 by lipopolysaccharide (LPS)-stimulated mouse peritoneal macrophages and human monocytes. It does not significantly affect the release of IL-6 or leukemia inhibitory factor (LIF). By itself AS-101 does not induce the release of any of these cytokines. Analysis of IL-10 and TNF alpha RNA levels using semiquantitative PCR reveals that AS-101 blocks the transcription of IL-10 mRNA, but does not significantly affect TNF alpha mRNA. Although both AS-101 and interferon (IFN)-gamma inhibit IL-10, AS-101, unlike IFN-gamma, does not prime macrophages for LPS-induced nitric oxide release and does not appear to significantly affect monocyte HLA-DR expression. Our data suggest that AS-101 is a partial IFN-gamma agonist and may explain the shift toward the release of Th-1 type cytokines observed in AS-101-treated patients.

Adjuvants, Immunologic↗

PubMed1997

Vesnarinone inhibits adenosine uptake in endothelial cells, smooth muscle cells and myocytes, and mediates cytoprotection.

Vesnarinone is a novel synthetic inotropic agent. Recently, it has been reported that vesnarinone inhibits adenosine uptake in the B-lymphocytoid cell line. Since extracellular adenosine is cardioprotective, we examined whether vesnarinone inhibits adenosine uptake in cells constituting the cardiovascular system. 1 microCi of -3H-adenosine was added to cells of the myocyte cell line (C2C12), human coronary smooth muscle cell line (HCASMC), human and bovine coronary endothelial cell lines (HCAEC and BCAEC), bovine arterial endothelial cell line (BAEC), and human umbilical venous endothelial cell line (HUVEC). After 10 s-5 min, cells were separated from free [3H]adenosine, and the radioactivity was measured. When 0.1-100 microM of vesnarinone was added to each cell line, the uptake of adenosine was inhibited dose-dependently {% inhibition of -3H-adenosine uptake at 10 and 30 microM of vesnarinone: 14 and 33% (C2C12), 47 and 72% (HCASMC), 37 and 58% (HCAEC), 42 and 68% (BCAEC), 19 and 68% (BAEC), 29 and 59% (HUVEC)}. The cellular viability of HCAEC exposed to 60 min of hypoxia and 60 min of reoxygenation increased from 34+/-5 to 67+/-6% (Trypan blue exclusion test) and 23+/-5 to 78+/-6% (LDH release), which was completely blunted by 8-sulfophenyltheophylline, an adenosine receptor antagonist, and was partially blunted by alpha,beta-methyleneadenosine 5'-diphosphate, an inhibitor of ecto-5'-nucleotidase. We also found that vesnarinone is cytoprotective against hypoxia and reoxygenation in C2C12 and HCASMC. We conclude that vesnarinone inhibits the uptake of adenosine in cardiovascular cells, which contributes to cytoprotection.

Adenosine↗

PubMed1997

Vesnarinone inhibits immune-mediated but not Fas (CD95) agonist-mediated hepatic injury.

Previous studies have shown that the administration of concanavalin A (ConA) into mice induces immune-mediated liver injury, which can be largely abrogated by neutralizing tumor necrosis factor(TNF)alpha. Vesnarinone is an experimental drug which is known to inhibit TNF alpha release. Here we demonstrate that vesnarinone inhibits ConA-induced hepatic injury. In a dose-dependent manner, vesnarinone inhibits in several mouse strains the increase of serum aminotransferase concentrations. additional experiments show that vesnarinone inhibits ConA-mediated accumulation of DNA fragmentation in the liver. Furthermore, the drug significantly reduces the levels of circulating TNF alpha and interleukin-6 (IL-6). Vesnarinone does not modulate TNF alpha and IL-6 action on hepatic cells, as shown by its failure to reduce the cytokine specific-stimulation of acute phase plasma proteins in the rat hepatoma H-35 cell line. Neither vesnarinone nor anti-TNF alpha protect against direct liver injury induced by a sublethal dose of agonist anti-Fas (CD95) antibody. Taken together, these results suggest that vesnarinone blocks hepatic injury, in part by inhibiting the release of TNF alpha in vivo.

Acute-Phase Reaction↗

PubMed1996

IL-4 and IL-13 modulate IL-10 release in endotoxin-stimulated murine peritoneal mononuclear phagocytes.

Several recent reports presented conflicting data on the action of IL-4 and IL-13 in regulating the release of proinflammatory cytokines by human monocytes. Here we show that the regulation of cytokine release by IL-4 and IL-13 could be either inhibitory or stimulatory in LPS-treated murine peritoneal macrophages. When macrophages were treated with IL-13 or IL-4, between 6 and 24 hr prior to endotoxin challenge, TNF alpha and IL-6 levels were significantly augmented. On the other hand, when the cells were cotreated with LPS plus IL-13 or IL-4, the release of TNF alpha and IL-6 was inhibited. These effects of IL-4 and IL-13 were associated with the modulation of IL-10; pretreatment resulted in a decrease, whereas cotreatment gave rise to a dramatic increase in IL-10 levels. The inhibitory effect of IL-4 and IL-13 on the release of TNF alpha was partially reversed by neutralizing anti-IL10 antibody, and the inhibition of IL-6 release was completely reversed by the antibody. These data suggest that the mechanism of action of IL-13 and IL-4 in modulating macrophage TNF alpha and IL-6 release partially involves IL-10.

Adjuvants, Immunologic↗

PubMed1996

The lack of an effect by insulin or insulin-like growth factor-1 in attenuating colon-2-mediated cancer cachexia.

In several studies, the anabolic hormones insulin-like growth factor-1 (IGF-1) and insulin attenuated several metabolic changes associated with cancer cachexia. In the present study, we evaluated the effect of these hormones on the cachexia associated with colon-26 (C-26) tumor. Healthy age-matched and tumor-bearing mice were treated with two daily doses of IGF-1 (50 micrograms/kg in toto), or insulin (1 U in toto). Determinants of cachexia were body and tumor weight, epididymal fat pad and serum glucose concentrations. Neither IGF-1 nor insulin treatment had a significant effect on the cachectic parameters of C-26-bearing mice. These hormones were biologically active, being capable of inducing weight gain in hypophysectomized mice and hypoglycemia, respectively. Although IGF-1 and insulin have been used to treat cancer-related weight loss, the research presented here suggests that the beneficial effect of these hormones is not universal.

Analysis of Variance↗

PubMed1995

Cyclic nucleotide phosphodiesterase type IV participates in the regulation of IL-10 and in the subsequent inhibition of TNF-alpha and IL-6 release by endotoxin-stimulated macrophages.

We have recently shown that PGE2 inhibits the release of TNF-alpha from LPS-stimulated murine peritoneal macrophages via a feedback mechanism involving IL-10. Here we demonstrate that a rolipram-sensitive phosphodiesterase (PDE) type IV participates in the regulation of IL-10 synthesis. Selective PDE IV inhibitors (rolipram and RO-20-1724), but not selective inhibitors of other types of PDE, significantly augment marcrophage IL-10 production and contribute to the inhibition of TNF-alpha and IL-6 release. The addition of rolipram to LPS-stimulated macrophages results in the accumulation of cAMP and in the significant augmentation of IL-10 release. Competitive PCR analysis reveals that the drug dramatically increases IL-10 mRNA, but does not affect TNF-alpha mRNA. The inhibitory effect of rolipram on TNF-alpha can be significantly but incompletely reversed by anti-IL-10 Ab, whereas the effect of the drug on IL-6 can be completely reversed by anti-IL-10. In endotoxemic mice, the administration of rolipram increases serum IL-10 and reduces TNF-alpha and IL-6 levels. Northern blot analysis of spleens from these mice shows that rolipram increases IL-10 mRNA, whereas TNF-alpha mRNA remains largely unchanged. These results suggest that a rolipram-sensitive PDE type IV is involved in the production of IL-10 and in turn contributes to the inhibition of TNF-alpha and IL-6 release.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗