Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:BIOD00017 (IFN-gamma)
 28,919 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calcium ionophore A23187 can mimic IFN-gamma-induced macrophage activation for intracellular Leishmania killing and secretion of L-arginine-derived nitrite. Because the effects of ionophore are not restricted to calcium mobilization but also involve alterations of phospholipid metabolism, we have examined the role of PGE2 in the activation process. Macrophages exposed to A23187 or IFN-gamma in the presence of LPS and FCS secreted significant amounts of PGE2 independently of the presence of L-arginine in the incubation medium. The addition of the cyclooxygenase inhibitor indomethacin or omission of FCS abrogated PGE2 secretion but had little effect on nitrite production or intracellular killing. The addition of exogenous PGE2, of agents increasing PGE2 production such as arachidonic acid and colchicine, or of an analogue of cAMP, dibutyryl cAMP inhibited A23187 + LPS-induced activation whereas that mediated by IFN-gamma + LPS remained unimpaired. Our results indicate that PGE2 can modulate activation induced by A23187 but not by IFN-gamma, probably by a process involving cAMP. Conceivably, ionophore can mimic IFN-gamma for the induction of activation but lacks the capacity to help maintain the activated state because of its inability to desensitize macrophages to negative regulation by PGE2, as suggested previously for IFN-gamma-dependent activation.
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PMID:Differential effects of prostaglandins on macrophage activation induced by calcium ionophore A23187 or IFN-gamma. 131 Jul 9

To characterize the requirements for the induction of an anergic state in immunocompetent cells we examined the effect of an increase in intracellular calcium concentration on the subsequent responsiveness of cytolytic T cells to antigenic stimulation in vitro. Pretreatment of a murine cytolytic T cell clone with the calcium-ionophore A23187 resulted in the induction of an anergic state characterized by a decrease in cytolytic activity and granule exocytosis upon Ag-specific stimulation. Furthermore, IFN-gamma synthesis declined whereas de novo synthesis of a yet unidentified protein with a molecular mass of 33 kDa as well as proliferative response of cells in response to exogenous IL-2 were unaffected. This state of partial unresponsiveness 1) could be prevented by concomitant pretreatment of cells with cyclosporin A or protein synthesis inhibitors and 2) was reversible within 48 h. Biochemical analysis of TCR-induced intracellular activation revealed a block in signal transduction before the activation of protein kinase C because cellular unresponsiveness could be bypassed by the phorbol ester PMA plus the calcium-ionophore A23187. However, phosphatidylinositol turnover was markedly inhibited in unresponsive cells that also did not show a calcium influx on stimulation with concanavalin A. We conclude that a rise in intracellular calcium in cytolytic T cells might not only be necessary for cellular activation but may also trigger the induction of a partial unresponsiveness to antigenic stimulation due to an inhibition in the early phase of signal transduction.
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PMID:Functional and biochemical characterization of a calcium-ionophore-induced state of unresponsiveness in a cytolytic T cell clone. 131 47

The adherence of cells to microvascular endothelium is important in a number of processes, including inflammatory responses and metastasis. It has been demonstrated that in human models, cytokines such as TNF, IL-1, IFN-gamma increase the adhesiveness of endothelium for cells of the immune and inflammatory system by stimulating the expression of cell adhesion molecules on endothelial cell surfaces. We and others have shown similar cytokine-induced endothelial adhesiveness for tumor cells in murine and human models. In contrast to the effect of those modulators, transforming growth factor-beta (TGF-beta) has been shown to inhibit the binding of human neutrophils and T lymphocytes to human endothelium, although the mechanism of TGF-beta action remains unknown. Little is known about the effect of TGF-beta on tumor cell-endothelial interaction. In the present study, we demonstrate that TGF-beta inhibits basal and TNF-enhanced binding of murine P815 mastocytoma cells to murine microvascular endothelium (MME). The alterations in MME mediated by TGF-beta, also lead to the inhibition of adherence of murine splenocytes, thymocytes, and human lymphoblastoid cells but do not inhibit adherence of murine B16 melanoma cells. The effect of TGF-beta is transient and inhibition of the endothelial adhesive phenotype is strongest 12 to 24 h after addition of the factor to MME. The TGF-beta-mediated inhibition of P815 basal binding to endothelium is dependent on protein synthesis because cycloheximide reverses the TGF-beta effect. TGF-beta does not appear to activate classical signal transduction pathways. Inhibitors of G proteins do not abolish TGF-beta action, protein kinase C and protein kinase A activators elicit an effect opposite to that of the factor, TGF-beta does not increase intracellular cAMP levels, and finally calcium-mobilizing agents do not mimic, but rather inhibit the effect of TGF-beta. However, TGF-beta-mediated inhibition of both basal binding and TNF-enhanced P815 binding to MME is completely abolished in the presence of the protein phosphatase inhibitor okadaic acid which suggests that TGF-beta may elicit its effect by stimulating protein phosphatase activity.
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PMID:Inhibition of basal and tumor necrosis factor-enhanced binding of murine tumor cells to murine endothelium by transforming growth factor-beta 1. 131 61

T-cell activation results in the production of multiple lymphokines. Efficient lymphokine gene expression appears to require both T-cell antigen receptor (TCR) signal transduction and an uncharacterized second or costimulatory signal. CD28 is a T-cell differentiation antigen that can generate intracellular signals that synergize with those of the TCR to increase T-cell activation and interleukin-2 (IL-2) gene expression. In these studies, we have examined the effect of CD28 signal transduction on granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), and gamma interferon (IFN-gamma) promoter activity. Stimulation of CD28 in the presence of TCR-like signals increases the activity of the GM-CSF, IL-3, and IFN-gamma promoters by three- to sixfold. As previously demonstrated for the IL-2 promoter, the IL-3 and GM-CSF promoters contain distinct elements of similar sequence which specifically bind a CD28-induced nuclear complex. Mutation of the CD28 response elements in the IL-3 and GM-CSF promoters abrogates the CD28-induced activity without affecting phorbol ester- and calcium ionophore-induced activity. UV cross-linking indicates that the CD28-induced nuclear complex contains polypeptides of approximately 35, 36, and 44 kDa. These studies indicate that the TCR and CD28-regulated signal transduction pathways coordinately regulate the transcription of several lymphokines and that the influence of CD28 signals on transcription is mediated by a common complex.
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PMID:Regulation of T-cell lymphokine gene transcription by the accessory molecule CD28. 132 52

Keratinocyte intercellular adhesion molecule (ICAM)-I expression is induced by interferon (IFN)-gamma. It has been previously reported that IFN-beta suppresses IFN-gamma-induced ICAM-I expression in A431 cells, a human squamous cell carcinoma cell line. In this study, the suppression mechanisms were investigated at the post second messenger level. Both 12-O-tetradecanoylphorbol-13-acetate (TPA) and calcium ionophore (A23187) induce ICAM-I expression in A431 cells. ICAM-I expression induced by either was not suppressed with cotreatment with IFN-beta. Furthermore, IFN-beta did not inhibit the translocation of protein kinase C (PKC) by TPA. It appears that the pathways involved in ICAM-I expression induced by activation of PKC or increased in intracellular Ca++ are not affected by IFN-beta.
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PMID:The effects of interferon-beta on phorbol ester or calcium ionophore-induced intercellular adhesion molecule-I expression in epidermal carcinoma cells. 135 13

Cloned CD4 T cells of the Th2 type make IL-4 and related cytokines upon receptor cross-linking, whereas cloned CD4 T cells of the Th1 type make IL-2, IFN-gamma, and TNF-beta. These two types of CD4 T cell are also reported to use distinct mechanisms of signal transduction. It has been reported that Th1 cells flux Ca2+ upon receptor cross-linking, whereas Th2 cells do not. We have noted that when cloned Th2 cells are exposed to high levels (20 U/ml) of IL-2, they show an altered phenotype. Such cells are much more sensitive to activation by certain antireceptor antibodies, they flux calcium upon receptor ligation without additional cross-linking with anti-Ig antibodies, and they make much larger amounts of IL-4. In addition, the organization of their TCR is altered, with increased levels of the TCR-eta chain and an increase in the extent of association of CD4 with CD3 and CD45, changes similar to those found in Th1 cells. These results suggest that there is no fundamental difference in the signal transduction apparatus of Th1 and Th2 cells; rather, the IL-2 made by Th1 cells may create similar phenotypic changes in these cells and thus create the impression of altered signal transduction mechanisms. These results do show that exposure to high levels of IL-2 can profoundly affect signal transduction in T cells. Furthermore, we found that the Ca2+ signal caused by CD3 antibodies seemed to differ in character from that caused by TCR antibodies suggesting that the use of CD3 antibodies is not always a good model for activation through the TCR.
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PMID:High levels of IL-2 alter signal transduction in cloned IL-4-producing CD4 T cells. 135 32

Lymphocyte function-associated Ag-1 (LFA-1) or CD11a/CD18 mediates lymphocyte adhesion to cultured vascular endothelial cells (EC). Thus, LFA-1 likely plays a major role in lymphocyte migration out of the blood, but there is little information on this in vivo. Small peritoneal exudate lymphocytes (sPEL) and lymph node (LN) lymphoblasts adhere to cytokine-activated EC and preferentially migrate to cutaneous inflammatory sites. The role of LFA-1 in the adherence and in vivo migration of these T cells was determined. Because of a lack of anti-rat LFA-1, mAb were prepared to rat T cells. One mAb, TA-3, inhibited homotypic aggregation; T cell proliferation to Ag, alloantigens, and mitogens; stained all leukocytes; and immunoprecipitated 170- and 95-kDa polypeptides from lymphocytes and neutrophils. TA-3 binding to lymphocytes also required Ca2+, but not Mg2+. Thus, TA-3 appears to react with rat LFA-1. TA-3 inhibited spleen T cell adhesion to unstimulated EC by 30% and to IFN-gamma, TNF-alpha, IL-1 alpha, and LPS stimulated EC by 50 to 60% but inhibited sPEL EC adhesion by only 10%. TA-3 also strongly inhibited anti-CD3-stimulated LN T cell adherence. The migration of spleen T cells to delayed-type hypersensitivity and skin sites injected with LPS, poly I:C, IFN-gamma, IFN-alpha/beta, and TNF was inhibited by 72 to 88% by TA-3, and was decreased by 50% to peripheral LN. TA-3 caused less but still 50 to 60% inhibition of sPEL migration to inflamed skin. Lymphoblast migration to skin was inhibited 40 to 80% and to PLN by 30%. Migration of lymphocytes from all sources to mesenteric LN was inhibited by 32 to 60%. In conclusion, LFA-1 mediates much of the adherence of spleen T cells and lymphoblasts to EC in vitro, most of the migration of these cells to dermal inflammation and about 50% of the homing of LN and spleen T cells to peripheral and mesenteric LN. sPEL are less dependent on LFA-1 for adhesion to EC in vitro and for migration to inflamed skin and LN in vivo.
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PMID:Inhibition of lymphocyte endothelial adhesion and in vivo lymphocyte migration to cutaneous inflammation by TA-3, a new monoclonal antibody to rat LFA-1. 135 70

Cloned human CD4+ T cell lines specific for the house dust mite Dermatophagoides pteronyssinus were used to map minimal T cell activation-inducing epitopes on the Group I allergen in D. pteronyssinus extracts (Der p I) molecule. Most of these Der p I-specific T cell clones expressed different TCR V alpha and V beta gene products. Using recombinant deletion proteins, three T cell epitopes were identified on the Der p I molecule; p45-67 and p117-143 were recognized by HLA-DR7-restricted T cells, whereas p94-104 was recognized in the context of HLA-DR2, DRw11 (DR5), and -DR8 molecules. This degenerate class II MHC restriction appears to be due to shared Phe and Asp residues at positions 67 and 70, respectively, in the third variable domain of the HLA-DR beta chain. All three T cell epitopes induced Th2-like cytokine production profiles by the Der p I-specific T cell clones, which were characterized by the production of very high levels of IL-4 and IL-5, as compared with those secreted by tetanus toxin-specific T cell clones derived from the same patients, but no or low amounts of IL-2 and IFN-gamma. This Th2-like production profile was, however, not an intrinsic property of the Der p I-specific T cells, but was dependent upon their mode of activation. Stimulation with Con A also induced very low or no measurable levels of IL-2 and IFN-gamma, whereas activation with TPA and the calcium ionophore A23187 resulted in the production of high levels of IL-4, IL-5, IL-2, and IFN-gamma. These results indicate that Der p I-specific T cell clones are not defective in their capacity to produce high levels of Th1 cytokines.
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PMID:T cell activation-inducing epitopes of the house dust mite allergen Der p I. Proliferation and lymphokine production patterns by Der p I-specific CD4+ T cell clones. 137 May 14

The preferential growth of CD3-CD2-CD11a/CD18- thymocytes was obtained by stimulation of CD2-CD3- thymic cells with low doses of PMA (0.5 ng/ml) and subsequent culture in the presence of recombinant interleukin-2 (100 U/ml). After 2-3 weeks, CD3-CD2-CD11a/CD18- thymocytes represented 40-60% of the total proliferating cells. Highly purified CD3-CD2-CD11a/CD18- cell populations were obtained by depletion of the CD11a/CD18+ thymocytes by immunomagnetic beads. Moreover, these populations proliferated for 2-5 weeks and did not change their surface phenotype. It is of note that these cells, despite the lack of CD2 and CD11a/CD18 adhesion molecules, could bind to umbilical vein endothelial cells as efficiently as did CD3+CD2+CD11a/CD18+ thymocytes. Furthermore we demonstrate that (a) CD56 molecule is involved in the adhesion of CD3-CD2-CD11a/CD18- thymic cells, but not of peripheral CD3-CD56+ lymphocytes, to untreated or IFN-gamma- and/or TNF-alpha-treated endothelium, (b) anti-CDw49d mAb could inhibit the adhesion of this thymus-derived population to either IFN-gamma- or TNF-alpha-treated endothelial cells but not to untreated endothelium, and (c) CD56 antigen expressed by these cultured thymocytes has a sialic acid content different from that of peripheral lymphocytes. Indeed, isoelectrofocusing analysis showed that CD56 molecule expressed on CD3-CD2-CD11a/CD18- thymocytes displayed an isoelectric point (pI 5.0) different from that of CD56 antigen expressed by peripheral NK cells (pI 4.7 and 5.4). Further, we noted that CD56 antigen showed the same pI 5.8 after desialylation obtained using neuraminidase treatment. Finally, CD3-CD2-CD11a/CD18- thymocytes mobilized Ca2+ and released TNF-alpha and IFN-gamma after treatment with lectins.
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PMID:Cultured human thymocytes lacking CD2 and CD11a/CD18 antigens are functional and adhere to endothelial cells via CD56 or CDw49d molecules. 137 47

The CD20 molecule is a unique phosphoprotein exclusively expressed on B cells during most stages of B cell ontogeny. We here report that rIL-4 down-regulates the expression of CD20 with anti-Leu-16 mAb (clone L27) on both unstimulated and anti-mu preactivated normal and leukemic B cells. None of the other recombinant lymphokines tested (IL-1, IL-2, IL-3, IL-6, IFN-alpha, and IFN-gamma, granulocyte/macrophage-CSF, transforming growth factor-beta, TNF-alpha, and lymphotoxin) decreased CD20 expression. Incubation of unstimulated or anti-mu preactivated B cells with IL-4 did not affect the steady state CD20 mRNA, suggesting that IL-4 exerted its effect mainly at a nontranscriptional level. Hence, IL-4 selectively down-regulates the CD20 epitope recognized by clone L27 without affecting seven other different epitopes, indicating that IL-4 acts by modifying the conformation of the CD20 molecule rather than by inhibiting its production or inducing its internalization. IL-4 most likely utilizes a protein kinase C-independent signal transduction pathway to modify CD20 molecule inasmuch as staurosporine, an inhibitor of protein kinase C, antagonizes phorbol esters (PMA) but not IL-4-induced CD20 down-regulation. In contrast, anti-CD40 mAb reverses the IL-4 but not the PMA inhibitory effect on CD20 expression. Given that CD20 may be part of a Ca2+ ion channel and plays a role in B cell activation and proliferation, it is proposed that the ability of anti-CD40 mAb to maintain the CD20 molecule in a given epitopic configuration on IL-4-stimulated B cells may be related to the long term proliferation of normal B cells that are strictly dependent on the presence of IL-4 and cross-linked anti-CD40 mAb for their continuous growth.
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PMID:IL-4 induces conformational change of CD20 antigen via a protein kinase C-independent pathway. Antagonistic effect of anti-CD40 monoclonal antibody. 137 68


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