The role of CD28 costimulation in the generation of cytotoxic T lymphocytes.
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Animals↗
Biomedical subjects
M Azuma
Publications and source records attributed to M Azuma.
Precipitation of crystallins from young rat lens by endogenous calpain.
The purpose of these experiments was to study the mechanism for precipitation of lens crystallins in cataract. An in vitro model was developed to activate the endogenous protease calpain II in the soluble proteins from young rat lens by addition of calcium in the presence of 120 mM KCl. Light-scattering, insoluble proteins were produced approximately 4-6 days after calpain II activation. Results showed that proteolysis was caused by activation of lens calpain II, proteolysis preceded precipitation by several days, and alpha-crystallin acted as a molecular chaperone against precipitation of crystallins caused by proteolysis. These data supported our hypothesis that calpain-induced proteolysis of the N-terminal arms of beta-crystallin polypeptides leads to a loss of normal oligomerization of beta-crystallin polypeptides and formation of abnormal insoluble aggregates, possibly stabilized by hydrophobic interactions.
Amino Acid Sequence↗
CD86 (B70/B7-2) on endothelial cells co-stimulates allogeneic CD4+ T cells.
In vascularized organ transplantation, vascular endothelial cells (EC) confronting recipient T cells are potentially significant APC initiating cellular immune responses that lead to rejection. In the present study, we studied the ability of human EC to stimulate allogeneic T cells and the co-stimulatory molecules involved in this response. On both human umbilical vein endothelial cells (HUVEC) and microvascular endothelial cells (MVEC), MHC class I, intercellular adhesion molecule (ICAM)-1 and CD86 were constitutively expressed as assessed by flow cytometry. After IFN-gamma treatment, MHC class II expression was induced, and MHC class I and ICAM-1 were up-regulated. In contrast, the expression of CD86 was unchanged and CD80 was undetectable even after IFN-gamma treatment. Highly purified CD4+ T cells proliferated in response to IFN-gamma-treated allogeneic HUVEC and MVEC, and this response was efficiently blocked by mAb to MHC class II, ICAM-1 and CD86. Furthermore, the addition of anti-CD86 mAb to the primary culture with allogeneic EC resulted in the induction of alloantigen-specific anergy. These results suggest that CD86 expressed on EC plays a critical role in initiating cellular immune responses to vascularized allografts and would be an important target for immune intervention.
Antibodies, Monoclonal↗
Analysis of the relationship between cellular thymidine kinase activity and virulence of thymidine kinase-negative herpes simplex virus types 1 and 2.
The virulence of thymidine kinase-negative herpes simplex virus type 1 (HSV-1; VRTK- strain) and type 2 (HSV-2; UWTK- strain) was studied in comparison with that of their parental strains (VR-3 and UW-268, respectively) in an encephalitis model of adult (4-week-old) and newborn (3-day-old) mice. Viral thymidine kinase (TK) activity was essential for the maximum expression of virulence of HSV-1, because the 50% lethal dose (LD50) of VRTK- was 60 times higher than that of VR-3 in the brains of newborn mice expressing high levels of cellular TK activity. However, the UWTK- strain showed that replication of the UWTK- strain was completely supported by cellular TK activity. This difference in the role of viral and cellular TKs for virus growth between HSV-1 and HSV-2 was¿ confirmed with the one-step growth of virus strains in L-M and L-M(TK-) cells.
Amino Acid Sequence↗
Spontaneous production of various cytokines except IL-4 from CD4+ T cells in the affected organs of sarcoidosis patients.
We investigated surface antigens and spontaneous cytokine production of T cells from bronchoalveolar lavage fluid (BALF) and aqueous humor (AH) from pulmonary sarcoidosis patients for a better understanding of the role of T cells in granuloma formation. The levels of CD3, CD11b, and CD28 antigen expression on freshly isolated T cells in the BALF of patients were significantly lower than those in peripheral blood lymphocytes (PBL) of either sarcoidosis patients or healthy donors (HD). In contrast, the levels of CD80 (B7/B7-1) and CD86 (B70/B7-2) antigen expression were significantly higher on these T cells and alveolar macrophages in the BALF of patients. Fifty-three T cell clones (TCC) established from the BALF and AH of the three sarcoidosis patients displayed primarily either CD4+ CD11b+ CD28+ or CD4+ CD11b- CD28- phenotypes. Most (61-90%) of these TCC spontaneously produced greater amounts of IL-1 alpha, IL-10, tumour necrosis factor (TNF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) than did TCC from the PBL from sarcoidosis patients or HD (P < 0.05). Interferon-gamma (IFN-gamma), IL-6, and IL-2, but not IL-4, were also produced by 40-48% of these TCC. These results suggest that CD4+ T cells of the affected organs of sarcoidosis patients are activated and involved in the immunopathogenesis of sarcoidosis through production of various cytokines.
Adult↗
Adhesion of Plasmodium falciparum-infected erythrocytes to human cells and secretion of cytokines (IL-1-beta, IL-1RA, IL-6, IL-8, IL-10, TGF beta, TNF alpha, G-CSF, GM-CSF.
The scientific interest in the physical interaction of Plasmodium falciparum-infected erythrocytes with host cells stems from the suggestion that excessive binding in the microvasculature leads to severe malaria. The authors studied, therefore, two parasites for their ability to adhere to normal human cells and to induce cytokine production, one parasite lacking a binding capacity (DD2) and one which adhered to CD36+ transfected CHO cells (MCAMP). The MCAMP parasites readily bound to platelets and erythrocytes and to monocytes, polymorphonuclear granulocytes and EBV-transformed B cells as seen by light and electron microscopy. Platelets were frequently attached in large numbers to the infected erythrocyte surface and groups of infected erythrocytes were sometimes held together by several platelets. Nine out of 17 cytokines tested were found to be secreted into the culture supernatants after 35 h of co-cultures containing monocytes or unfractionated peripheral blood mononuclear cells (PBMC) and parasites (IL-1RA, IL-6, IL-8, IL-10, TGF beta, TNF alpha, G-CSF, IL-1-beta, and GM-CSF). Three additional cytokines were also present in low levels (< 200 pg/ml, IL-2, IL-4, IFN gamma) in the culture supernatants after incubation of the cells for 4 days. TNF alpha, IL-RA, and IL-8 were secreted from polymorphonuclear granulocytes, LGLs and T cells. Platelets and, to a lesser degree, monocytes and T cells secreted large amounts of TGF beta (10-30 ng/ml). Cytokines may participate in the pathogenesis but also the suppression of immune responses seen during acute malarial infections.
Animals↗
Proteolytic enzymes in salivary extravasation mucoceles.
We examined the content of type IV collagenases and plasminogen activators (PAs) in luminal fluid of four extravasation mucoceles by means of gelatin or casein zymography. Immunohistochemical staining for type IV collagenases and PAs was performed to identify the possible source of these enzymes. The luminal fluid examined by gelatin zymography showed a high level of type IV collagenases compared with saliva from Wharton's duct. PAs were detected in only one of the cases by casein zymography, and none was detected in the saliva. By immunohistochemical staining, type IV collagenases and PAs were detected in duct and myoepithelial cells of the adjacent salivary gland and in macrophages and fibroblasts of the cyst wall. The results suggest that proteolytic enzymes are involved in the pathogenesis of mucoceles.
Adolescent↗
Identification of varicella-zoster virus strains by PCR analysis of three repeat elements and a PstI-site-less region.
We established a method of identifying varicella-zoster virus (VZV) strains, especially those of the Oka vaccine, in patients with clinical VZV infections. The DNAs of 30 clinically isolated strains and 4 laboratory strains including the Oka vaccine strain and its parent VZV strain, were analyzed by PCR with four sets of primers for the four variable regions, R2, R4, R5, and a region without a PstI site (PS). R4 was unstable in four laboratory VZV strains and was excluded from the study. The other regions were stable in several passages in cell culture. The number of copies in R2 and R5 were distributed from 2 to 13 and from 1 to 3, respectively, in the strains analyzed. The vaccine strain had seven copies in R2 and two copies in R5, and it was PS negative. Among 30 clinical isolates, 3, 23, and 11 strains had the same characteristics as the vaccine strain in R2, R5, and PS, respectively. Therefore, by this method, 97.2% of the isolates were distinguished from the Oka vaccine strain. This strategy will be useful in diagnosing VZV infections induced by the vaccine strain.
Adult↗
Cloning, purification, and properties of a cofactor-independent glutamate racemase from Lactobacillus brevis ATCC 8287.
A glutamate racemase gene of Lactobacillus brevis ATCC 8287 was cloned into Escherichia coli TM93 by the phenotypic complementation of a phosphoenolpyruvate carboxylase deficiency on minimum agar medium containing D-glutamate. The gene was localized to a 1.4-kb HindIII-EcoRI DNA fragment and the total nucleotide sequence of the fragment was analyzed. The gene has typical promoter and SD sequences which appeared to function in E. coli. The deduced amino acid sequence of the enzyme had 276 amino acids and the molecular weight was calculated as 29,426. Two cysteine residues and their surrounding regions of the enzyme are homologous to those of other cofactor-independent racemases. The glutamate racemase was purified from recombinant E. coli to homogeneity and characterized. The enzyme required no cofactors for the activity, and retained its activity even in 2 M (300 g/l) L-glutamate.
Amino Acid Isomerases↗
Pituitary adenylate cyclase-activating polypeptide stimulates the synthesis of dopamine in cultured bovine adrenal chromaffin cells.
The effect of pituitary adenylate cyclase-activating polypeptide1-38 (PACAP1-38) on the synthesis of dopamine in cultured bovine adrenal chromaffin cells was examined. PACAP1-38 stimulated [14C]dopamine synthesis from [14C]tyrosine, in a concentration-dependent manner, causing maximal stimulation at 10(-7)M. This stimulatory action of PACAP1-38 was not significantly inhibited by staurosporine (an inhibitor of protein kinase C) or in the cells in which protein kinase C was down-regulated by prolonged exposure to TPA (an activator of protein kinase C), whereas it was partially attenuated in Ca(2+)-free medium. PACAP1-38 increased the formation of [3H] inositol phosphates, [Ca2+]i, 45Ca2+ uptake and cAMP level. The peptide also stimulated the phosphorylation of tyrosine hydroxylase, the enzyme catalyzing the rate-limiting step in dopamine synthesis. Dopamine synthesis and tyrosine hydroxylase phosphorylation stimulated by the maximal effective concentration of dibutyryl cAMP or high K+, which activates Ca2+ uptake, were further enhanced by PACAP1-38. These results indicated that PACAP1-38 may stimulate the activities of cAMP- and calcium-dependent protein kinases in cultured bovine adrenal chromaffin cells, resulting in increase in the synthesis of dopamine probably by stimulation of phosphorylation of tyrosine hydroxylase.
Animals↗
Perforin-positive leukemic cell infiltration in the heart of a patient with T-cell prolymphocytic leukemia.
Here we report a rare case of T-cell prolymphocytic leukemia in whom leukemic killer cells, expressing a cytolytic factor perforin, infiltrated the heart. Perforin may have directly injured myocardial cells which showed marked expression of human leukocyte antigens (HLAs) and intercellular adhesion molecule-1 (ICAM-1) as well as costimulatory molecules B7 and B70, which are ligands for CD28 expressed on T-cells. In spite of chemotherapy against leukemic cells, this autoimmune process finally caused fatal congestive heart failure.
Adult↗
Proteolysis by calpain is an underlying mechanism for formation of sugar cataract in rat lens.
To confirm the effect of a new aldose reductase inhibitor (ARI), rat lenses were cultured with xylose. ARI prevented opacities and reduced lens hydration caused by xylose. Next, cataract was produced by feeding a diet containing 50% galactose. ARI was tested for amelioration of cataract. On day 19 after feeding of galactose, nuclear cataracts were visible in 75% of the animals receiving only galactose, while nuclear cataracts were not observed in animals treated with ARI. In galactose cataract, lens hydration and calcium were significantly increased. Calpain in soluble and insoluble fractions was decreased. Alpha- and beta-crystallins were proteolyzed. These changes were inhibited by administration of ARI. These results suggested that proteolysis by calpain is an underlying mechanism in formation of sugar cataract in rat lens.
Aldehyde Reductase↗
Role of B70/B7-2 in CD4+ T-cell immune responses induced by dendritic cells.
Dendritic cells (DC) are potent antigen-presenting cells (APC). However, the molecular basis underlying this activity remains incompletely understood. To address this question, we generated murine monoclonal antibodies (mAb) against human peripheral blood-derived DC. One such antibody, designated IT209, stained differentiated DC and adherent monocytes, but failed to stain freshly isolated peripheral blood mononuclear cells (PBMC). The antigen recognized by IT209 was identified as B70 (B7-2; also recently identified as CD86). Using this mAb we studied the role of B70 in CD4+ T-cell activation by DC in vitro. IT209 partly inhibited the proliferative response of CD4+ T cells to allogeneic DC and to recall antigens, such as tetanus toxoid (TT) and purified protein derivative (PPD) of tuberculin, presented by autologous DC. More importantly, the mAb had a potent inhibitory effect on the primary response of CD4+ T cells to autologous DC pulsed with human immunodeficiency virus (HIV) gp160 or keyhole limpet haemocyanin (KLH). Adherent monocytes, despite their expression of B70, failed to induce T-cell responses to these antigens. IT209-mediated inhibition of CD4+ T-cell responses was equivalent to that produced by anti-CD25 mAb, whereas an anti-CD80 mAb was only marginally inhibitory and did not augment the effect of IT209. These findings indicate that the B70 antigen plays an important role in DC-dependent CD4+ T-cell activation, particularly in the induction of primary CD4+ T-cell responses to soluble antigens. However, since activated monocytes, despite their expression of B70, failed to prime naive T cells to these antigens, our results suggest that additional molecules contribute to the functions of DC in CD4+ T-cell activation.
Antibodies, Monoclonal↗
[An immunohistochemical study on microtubule associated protein-1 of normal and malignant human gastric tissue].
Microtubule Associated Protein-1 (MAP-1) plays an important role for polymerization of tublin to microtubules. Indirect immunohistochemistry using anti-MAP-1 monoclonal antibody was performed in this study. Difference of internuclear MAP-1 staining patterns between normal and malignant human gastric tissues was investigated. Normal gastric tissue had localized MAP-1 positive staining nucleus in corresponding area of generative cell zone of gastric gland. On the other hand, the 75% cases of gastric cancer showed numerous labeled nuclei in most of the cancer tissues, and 25% cases did not show positive staining of nuclei in cancer tissue. The nuclei staining were classified as negative (-), weak granular (+) and strong punctate (++). The tissue staining pattern was fallen into two patterns, uniform and ununiform stained groups. Positive nuclei staining for MAP-1 and staining pattern had no correlation with histological type of gastric cancer, vessel invasion and lymph node metastasis. But post operative 5-years survival rares were 77.3% in uniform stained group and 30.0% in ununiform stained group. Thus, there were relationship between the post operative survival ratio and the staining pattern of nuclei. Internuclear MAP-1 staining pattern was considered to be one of effective parameters on prognostic sign in gastric cancer.
Antibodies, Monoclonal↗
FK506 and cyclosporin A inhibit granulocyte/macrophage colony-stimulating factor production by mononuclear cells in asthma.
Bronchial asthma is associated with eosinophilic inflammation and expression of T-cell-derived cytokines, which influence eosinophilic function. FK506, a newly established immunosuppressive agent, may have potential as a therapeutic instrument for asthma because of its suppressive effect on T-cell activation. To assess this, we compared the inhibitory effects of FK506 and cyclosporin A on production of granulocyte/macrophage colony-stimulating factor and interleukin-5 by interleukin-2- or Dermatophagoides farinae-stimulated mononuclear cells from patients with asthma, and their contribution to proliferation and survival of eosinophils in vitro. FK506 inhibited granulocyte/macrophage colony-stimulating factor production by stimulated mononuclear cells from asthma patients at lower concentrations than cyclosporin A. Both drugs inhibited eosinophil proliferation and survival activity from mononuclear cells at comparable concentrations. Interleukin-5 production by stimulated mononuclear cells was also inhibited both by FK506 and cyclosporin A. We conclude that both FK506 and cyclosporin A have potential for therapy of bronchial asthma.
Asthma↗
Observation of a spin gap in SrCu2O3 comprising Ssin-12 quasi-1D two-leg ladders.
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Journal Article↗
B70/B7-2 is identical to CD86 and is the major functional ligand for CD28 expressed on human dendritic cells.
Dendritic cells comprise a system of highly efficient antigen-presenting cells involved in the initiation of T cell responses. Herein, we investigated the role of the CD28 pathway during alloreactive T cell proliferation induced by dendritic-Langerhans cells (D-Lc) generated by culturing human cord blood CD34+ progenitor cells with granulocyte/macrophage colony-stimulating factor and tumor necrosis factor alpha. In addition to expressing CD80 (B7/BB1), a subset of D-Lc expressed B70/B7-2. Binding of the CTLA4-Ig fusion protein was completely inhibited by a combination of monoclonal antibodies (mAbs) against CD80 and B70/B7-2, indicating the absence of expression of a third ligand for CD28/CTLA-4. It is interesting to note that mAbs against CD86 completely prevented the binding of CTLA4-Ig in the presence of mAbs against CD80 and bound to a B70/B7-2-transfected fibroblast cell line, demonstrating that the B70/B7-2 antigen is identical to CD86. CD28 triggering was essential during D-Lc-induced alloreaction as it was inhibited by mAbs against CD28 (9 out of 11 tested). However, none of six anti-CD80 mAbs demonstrated any activity on the D-Lc-induced alloreaction, though some were previously described as inhibitory in assays using CD80-transfected cell lines. In contrast, a mAb against CD86 (IT-2) was found to suppress the D-Lc-dependent alloreaction by 70%. This inhibitory effect was enhanced to > or = 90% when a combination of anti-CD80 and anti-CD86 mAbs was used. The present results demonstrate that D-Lc express, in addition to CD80, the other ligand for CTLA-4, CD86 (B70/B7-2), which plays a primordial role during D-Lc-induced alloreaction.
Abatacept↗
The tissue distribution of the B7-2 costimulator in mice: abundant expression on dendritic cells in situ and during maturation in vitro.
B7-2 is a recently discovered, second ligand for the CTLA-4/CD28, T cell signaling system. Using the GL-1 rat monoclonal antibody (mAb), we monitored expression of B7-2 on mouse leukocytes with an emphasis on dendritic cells. By cytofluorography, little or no B7-2 was detected on most cell types isolated from spleen, thymus, peritoneal cavity, skin, marrow, and blood. However, expression of B7-2 could be upregulated in culture. In the case of epidermal and spleen dendritic cells, which become highly immunostimulatory for T cells during a short period of culture, the upregulation of B7-2 was dramatic and did not require added stimuli. Lipopolysaccharide did not upregulate B7-2 levels on dendritic cells, in contrast to macrophages and B cells. By indirect immunolabeling, the level of staining with GL-1 mAb exceeded that seen with rat mAbs to several other surface molecules including intercellular adhesion molecule 1, B7-1, CD44, and CD45, as well as new hamster mAbs to CD40, CD48, and B7-1/CD80. Of these accessory molecules, B7-2 was a major species that increased in culture, implying a key role for B7-2 in the functional maturation of dendritic cells. B7-2 was the main (> 90%) CTLA-4 ligand on mouse dendritic cells. When we applied GL-1 to tissue sections of a dozen different organs, clear-cut staining with B7-2 antigen was found in many. B7-2 staining was noted on liver Kupffer cells, interstitial cells of heart and lung, and profiles in the submucosa of the esophagus. B7-2 staining was minimal in the kidney and in the nonlymphoid regions of the gut, and was not observed at all in the brain. In the tongue, only rare dendritic cells in the oral epithelium were B7-2+, but reactive cells were scattered about the interstitial spaces of the muscle. In all lymphoid tissues, Gl-1 strongly stained certain distinct regions that are occupied by dendritic cells and by macrophages. For dendritic cells, these include the thymic medulla, splenic periarterial sheaths, and lymph node deep cortex; for macrophages, the B7-2-rich regions included the splenic marginal zone and lymph node subcapsular cortex. Splenic B7-2+ cells were accessible to labeling with GL-1 mAb given intravenously. Dendritic cell stimulation of T cells (DNA synthesis) during the mixed leukocyte reaction was significantly (35-65%) blocked by GL-1.(ABSTRACT TRUNCATED AT 400 WORDS)
Abatacept↗