Establishment and characterization of nurse cell-like stromal cell lines from synovial tissues of patients with rheumatoid arthritis.
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OBJECTIVE: To investigate the features of synovial stromal cells established from patients with rheumatoid arthritis (RA), and to define these cells as nurse cells. METHODS: Synovial nurse-like stromal cell lines (RA-SNCs) were established from patients with RA. These cell lines were examined for morphology, pseudoemperipolesis activity, cell surface markers, and cytokine production. The interaction between these RA-SNCs and a synovial tissue B cell clone was also examined. RESULTS: RA-SNCs had nurse cell activity. They spontaneously produced interleukin-6 (IL-6), IL-8, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor. Furthermore, they produced IL-1beta and tumor necrosis factor alpha and expressed higher levels of the other cytokines after coculture with the B cell clone. Proliferation and Ig production by the B cell clone were dependent on direct contact with RA-SNCs. CONCLUSION: These results indicate that the RA-SNCs were nurse cells. The findings suggest that RA-SNCs may play an important role in the pathogenesis of RA by producing large amounts of cytokines and maintaining infiltrating lymphocytes. (+info)
gp49B1 inhibits IgE-initiated mast cell activation through both immunoreceptor tyrosine-based inhibitory motifs, recruitment of src homology 2 domain-containing phosphatase-1, and suppression of early and late calcium mobilization.
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We define by molecular, pharmacologic, and physiologic approaches the proximal mechanism by which the immunoglobulin superfamily member gp49B1 inhibits mast cell activation mediated by the high affinity Fc receptor for IgE (FcepsilonRI). In rat basophilic leukemia-2H3 cells expressing transfected mouse gp49B1, mutation of tyrosine to phenylalanine in either of the two immunoreceptor tyrosine-based inhibitory motifs of the gp49B1 cytoplasmic domain partially suppressed gp49B1-mediated inhibition of exocytosis, whereas mutation of both abolished inhibitory capacity. Sodium pervanadate elicited tyrosine phosphorylation of native gp49B1 and association of the tyrosine phosphatases src homology 2 domain-containing phosphatase-1 (SHP-1) and SHP-2 in mouse bone marrow-derived mast cells (mBMMCs). SHP-1 associated transiently with gp49B1 within 1 min after coligation of gp49B1 with cross-linked FcepsilonRI in mBMMCs. SHP-1-deficient mBMMCs exhibited a partial loss of gp49B1-mediated inhibition of FcepsilonRI-induced exocytosis at concentrations of IgE providing optimal exocytosis, revealing a central, but not exclusive, SHP-1 requirement in the counter-regulatory pathway. Coligation of gp49B1 with cross-linked FcepsilonRI on mBMMCs inhibited early release of calcium from intracellular stores and subsequent influx of extracellular calcium, consistent with SHP-1 participation. Because exocytosis is complete within 2 min in mBMMCs, our studies establish a role for SHP-1 in the initial counter-regulatory cellular responses whereby gp49B1 immunoreceptor tyrosine-based inhibition motifs rapidly transmit inhibition of FcepsilonRI-mediated exocytosis. (+info)
Preparation of antibodies directed to the Babesia ovata- or Theileria sergenti-parasitized erythrocytes.
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To investigate the surface antigens of the bovine red blood cells (RBCs) parasitized by Babesia ovata or Theileria sergenti, attempts were made to produce monoclonal antibodies (mAbs) with BALB/c mice. Comparable numbers of hybridomas producing anti-piroplasm mAbs, as well as anti-bovine RBC mAbs, were obtained from the mice immunized with B. ovata- or T. sergenti-PRBCs. However, mAbs directed to the surface of parasitized RBCs (PRBCs) were obtained only from the mice immunized with B. ovata-PRBCs, but not from those immunized with T. sergenti-PRBCs. When serum samples from the immunized mice and the infected cattle were examined, antibodies recognizing B. ovata-PRBC surface were detected in the sera against B. ovata, but analogous antibodies were undetectable in the sera against T. sergenti, despite that the sera showed substantial antibody titers to T. sergenti piroplasms. The results suggest that significant antigenic modifications occur on the surface of B. ovata-PRBCs, but not on the surface of T. sergenti-PRBCs. (+info)
Suppression of atherosclerotic development in Watanabe heritable hyperlipidemic rabbits treated with an oral antiallergic drug, tranilast.
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BACKGROUND: Inflammatory and immunological responses of vascular cells have been shown to play a significant role in the progression of atheromatous formation. Tranilast [N-(3,4-dimethoxycinnamoyl) anthranillic acid] inhibits release of cytokines and chemical mediators from various cells, including macrophages, leading to suppression of inflammatory and immunological responses. This study tested whether tranilast may suppress atheromatous formation in Watanabe heritable hyperlipidemic (WHHL) rabbits. METHODS AND RESULTS: WHHL rabbits (2 months old) were given either 300 mg x kg-1 x d-1 of tranilast (Tranilast, n=12) or vehicle (Control, n=13) PO for 6 months. Tranilast treatment was found to suppress the aortic area covered with plaque. Immunohistochemical analysis showed that there was no difference in the percentage of the RAM11-positive macrophage area and the frequency of CD5-positive cells (T cells) in intimal plaques between Tranilast and Control. Major histocompatibility complex (MHC) class II expression in macrophages and interleukin-2 (IL-2) receptor expression in T cells, as markers of the immunological activation in these cells, was suppressed in atheromatous plaque by tranilast treatment. Flow cytometry analysis of isolated human and rabbit peripheral blood mononuclear cells showed that an increase in expression both of MHC class II antigen on monocytes by incubation with interferon-gamma and of IL-2 receptor on T cells by IL-2 was suppressed by the combined incubation with tranilast. CONCLUSIONS: The results indicate that tranilast suppresses atherosclerotic development partly through direct inhibition of immunological activation of monocytes/macrophages and T cells in the atheromatous plaque. (+info)
Cell surface-associated lipoteichoic acid acts as an adhesion factor for attachment of Lactobacillus johnsonii La1 to human enterocyte-like Caco-2 cells.
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The influence of pH on the adhesion of two Lactobacillus strains to Caco-2 human intestinal cells was investigated. One strain, Lactobacillus johnsonii La1, was adherent at any pH between 4 and 7. The other one, L. acidophilus La10, did not attach to this cell line under the same experimental conditions. On the basis of these results, we used the monoclonal antibody technique as a tool to determine differences on the surface of these bacteria and to identify a factor for adhesion. Mice were immunized with live La1, and the hybridomas produced by fusion of spleen cells with ONS1 cells were screened for the production of antibodies specific for L. johnsonii La1. A set of these monoclonal antibodies was directed against a nonproteinaceous component of the L. johnsonii La1 surface. It was identified as lipoteichoic acid (LTA). This molecule was isolated, chemically characterized, and tested in adhesion experiments in the same system. The adhesion of L. johnsonii La1 to Caco-2 cells was inhibited in a concentration-dependent way by purified LTA as well as by L. johnsonii La1 culture supernatant that contained LTA. These results showed that the mechanism of adhesion of L. johnsonii La1 to human Caco-2 cells involves LTA. (+info)
Characterization of prethymic progenitors within the chicken embryo.
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The thymic primordium in both birds and mammals is first colonized by cells emerging from the intra-embryonic mesenchyme but the nature of these precursors is poorly understood. We demonstrate here an early embryonic day 7 prethymic population with T lymphoid potential. Our work is a phenotypic analysis of, to date, the earliest embryonic prethymic progenitors arising in the avian para-aortic area during ontogeny. The phenotype of these cells, expressing the cell surface molecules alpha2beta1 integrin, c-kit, thrombomucin/MEP21, HEMCAM and chL12, reflects functional properties required for cell adhesion, migration and growth factor responsiveness. Importantly, the presence of these antigens was found to correlate with the recolonization of the recipient thymus following intrathymic cell transfers. These intra-embryonic cells were also found to express the Ikaros transcription factor, the molecular function of which is considered to be prerequisite for embryonic lymphoid development. (+info)
Two-gene control of the expression of a murine Ia antigen.
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Two dimensional polyacrylamide gel electrophoresis of Non-Idet P-40 extracts and of specific Ia immunoprecipitates from [35S]methionine-labeled mouse spleen lymphocytes has revealed that the cell surface expression of some Ia antigens appears to be controlled by two genes. One locus, which maps in the I-A subregion, is probably the structural gene for an Ia polypeptide chain. The second locus, which maps between the I-J and H-2D regions, controls whether this I-A encoded molecule (Ae) remains in the cytoplasm or is modified and expressed on the cell surface. Complementation between these two loci allowing surface expression of Ae can occur in the cis or trans chromosomal position. Both the I-A molecule and a polypeptide chain coded for by a locus in I-E are coprecipitated by anti-I-E antibodies, suggesting that these two chains are associated with each other as a multisubunit complex in the cell. Because the ability to complement I-A for Ae expression is a property only of those strains which synthesize an I-E-encoded protein, it is likely that the I-E product itself is regulating the expression of Ae. These observations suggest several mechanisms by which interaction between two I region loci can generate new cell surface molecules. As a result, they may have important implications for understanding the molecular basis of two gene control of immune responsiveness and immune suppression. (+info)
Immunomodulatory effects of glycine on LPS-treated monocytes: reduced TNF-alpha production and accelerated IL-10 expression.
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Cytokines play a pivotal role in the pathogenesis of septic shock. Proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) stimulate the progression of septic shock whereas the anti-inflammatory cytokine IL-10 has counterregulative potency. The amino acid glycine (GLY) has been shown to protect against endotoxin shock in the rat by inhibiting TNF-alpha production. In the current study we investigated the role of GLY on lipopolysaccharide (LPS) -induced cell surface marker expression, phagocytosis, and cytokine production on purified monocytes from healthy donors. GLY did not modulate the expression of HLA-DR and CD64 on monocytes, whereas CD11b/CD18 expression (P<0.05) and E. coli phagocytosis (P<0.05) decreased significantly. GLY decreased LPS-induced TNF-alpha production (P<0.01) and increased IL-10 expression of purified monocytes. Similarly, in a whole blood assay, GLY reduced TNF-alpha (P<0.0001) and IL-1beta (P<0.0001) synthesis and increased IL-10 expression (P<0.05) in a dose-dependent manner. The inhibitory effects of GLY were neutralized by strychnine, and the production of IL-10 and TNF-alpha was augmented by anti-IL-10 antibodies. Furthermore, GLY decreased the amount of IL-1beta and TNF-alpha-specific mRNA. Our data indicate that GLY has a potential to be used as an additional immunomodulatory tool in the early phase of sepsis and in different pathophysiological situations related to hypoxia and reperfusion. (+info)