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Biomedical subjects

A Meager

Publications and source records attributed to A Meager.

At least 37 records · Page 2Linked to original sources
PubMed1997

Treatment of metastatic renal cell carcinoma with subcutaneous interleukin 2: evidence for non-renal clearance of cytokines.

The circulating cytokine concentrations following administration of subcutaneous recombinant interleukin 2 (IL-2) in combination with interferon alpha and 5-fluorouracil used to treat advanced renal cancer were studied. One patient was anephric and on dialysis, and seven had normal biochemical renal function, although five had undergone single nephrectomy. The pharmacokinetics of IL-2 and changes in IL-6 and tumour necrosis factor (TNF)-alpha were essentially similar in all patients including the anephric patient, irrespective of the periods of dialysis, although at some time points, IL-2 concentrations were slightly higher in the anephric patient than in the others. These results show that for subcutaneous administration of low-dose IL-2, renal clearance of IL-2 is not important. This contrasts with high-dose, intravenous IL-2 where blood concentrations are higher and renal clearance seems to occur, perhaps because of saturation of the non-renal mechanisms of clearance. The subcutaneous route is certainly preferred if IL-2 is used in anephric patients and in those with impaired renal function, and it may be generally preferred for most purposes.

Adult↗
PubMed1997

Transforming growth factor-beta induced by live or ultraviolet-inactivated equid herpes virus type-1 mediates immunosuppression in the horse.

Up to 21 days after exposure to live or ultraviolet-inactivated equid herpesvirus type-1 (EHV-1) autologous serum from ponies caused an immunosuppressive effect if incorporated into T-cell proliferation assays to EHV-1. The suppressive factor in the sera of ponies also inhibited T-cell response to phytohaemagglutinin. Increased levels of circulating activated transforming growth factor-beta 1 (TGF-beta 1) were detected, and the suppressive activity of the serum could be reversed by antibody to TGF-beta 1. In a challenge experiment the ponies which exhibited circulating TGF-beta 1 activity succumbed to infection while the ones with similar magnitudes of T-cell responses, but no TGF-beta 1 activity, were protected. A definition of this immunosuppressive mechanism and its mode of induction must be central to the design of vaccines and to an understanding of the pathogenesis of EHV-1.

Animals↗
PubMed1997

Interferon standardization and designations.

A large number of different human and nonhuman interferon (IFN) preparations are now available for either research purposes or commercial use. Consistency of results can be achieved only through rigorous application of biologic standards and individual species designation. International standards for the potency determinations of these preparations have been produced in accordance with World Health Organization (WHO) guidelines and are available for calibrating assays. Until recently, potency has been assessed purely as a measure of antiviral activity expressed in international units. Other biologic properties are now also being considered, including antiproliferation and immunomodulation. Indirect methods of measuring IFN, such as radioimmunoassay or enzyme immunoassay, if fully validated, may also provide useful estimates of function. Reference antisera are useful for characterizing IFN preparations and for monitoring neutralization assays for detecting anti-IFN antibodies but should not have a function in assay calibration. Factors to be considered when referring to specific designations for pure IFN species include distinctions for the species of origin, any mutant or hybrid forms, the method of production, and the presence of additional glycosylation.

Animals↗
PubMed1997

Natural autoantibodies to interferons.

Natural antibodies that appear to have arisen in the absence of direct antigenic stimulation often are present in the circulation. In healthy individuals, they are of low prevalence and generally show low affinity to their respective antigens, whereas in autoimmune disease, their frequency and affinity toward specific antigens are in many cases increased. In some autoimmune disease, the spontaneous occurrence of autoantibodies to antigens that are apparently unrelated to symptoms or pathology has been observed. For example, antibodies to interferon-alpha (IFN-alpha) have been observed in patients with systemic lupus erythematosus but appear to be of no clinical significance. Natural autoantibodies to IFN-alpha have also been found in other patients, including those with insulin-dependent diabetes mellitus, heart disease, or cancer and patients who have just received allogeneic bone marrow transplantation. A major property of IFN-alpha autoantibodies is their capacity to both bind to and neutralize the biologic activity of a range of IFN-alpha subtypes and natural IFN-alpha preparations. Their origins and significance remain a matter for debate.

Antigen-Antibody Reactions↗
PubMed1996

An anti-cytokine bioactivity assay for interferons-alpha, -beta and -omega.

Interferons-alpha and -beta (IFN-alpha and -beta) are cytokines that are widely known to induce potent anti-viral activity. However, it has become increasingly apparent that IFN-alpha and -beta exert a variety of other biological effects, including anti-tumour and immunomodulatory activities and are increasingly used clinically to treat a range of malignancies, myelodysplasias and autoimmune diseases, e.g., IFN-beta for multiple sclerosis. The most widely used bioassays for the IFNs are based on their anti-viral activity, but these do not predict the biological activity of the IFNs in anti-tumour and immunomodulatory therapies. Thus, we have developed anti-cytokine-based bioassays that may be more reflective of such activity and which have several advantages over existing anti-viral bioassays. The anti-cytokine bioassay is based on the ability of IFN-alpha, -beta and -omega to inhibit granulocyte-macrophage-colony-stimulating factor (GM-CSF) induced proliferation of the erythroleukaemic cell line TF-1. This assay can take only 24 h, is sensitive to 200 fg (0.04 IU) IFN-alpha or -beta and 100 fg (0.02 IU) IFN-omega and is able to detect down to these levels in serum or plasma samples. The usefulness of anti-cytokine bioassays for IFN-alpha, -beta and -omega is not restricted to the GM-CSF/TF-1 cell format and other alternatives are available, such as erythropoietin (EPO)/TF-1 cells and EPO/UT-7-EPO cells. These assays can be made specific for each of the IFNs by including neutralising antibodies in the bioassay.

Humans↗
PubMed1996

Bioimmunoassays for proinflammatory cytokines involving cytokine-induced cellular adhesion molecule expression in human glioblastoma cell lines.

Twelve human glioblastoma/astrocytoma cell lines were tested for cellular adhesion molecule expression following cytokine induction in order to identify a cell line that would be suitable for functional cytokine bioimmunoassays. Many of the glioblastoma/astrocytoma cell lines were shown to inducibly express intercellular adhesion molecule-1 (ICAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-1) following stimulation with interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), tumour necrosis factor-beta (TNF-beta), and interferon-gamma (IFN-gamma), but not with any of the several other cytokines tested. The cell line U-138MG, a human glioblastoma-derived line, was the most sensitive one to IL-1 alpha/beta, TNF-alpha/beta and IFN-gamma for ICAM-1 expression, comparing well with proinflammatory cytokine-induced ICAM-1 expression in the endothelial cell hybrid EA-hy926 line, and was shown to be useful for the functional assay of the biological potencies of these individual cytokines. Such bioimmunoassays, which are developed by routine ELISA techniques, should provide valuable alternatives to existing bioassays for these cytokines.

Astrocytoma↗
PubMed1996

IL-4 and TNF-alpha-mediated proliferation of the human megakaryocytic line M-O7E is regulated by induced autocrine production of GM-CSF.

In this study, the authors examined the effects of recombinant human interleukin 4 (rhIL-4) and recombinant human tumour necrosis factor alpha (rhTNF-alpha) alone or in combination on proliferation of the human cytokine dependent myeloid cell line, M-O7e. While rhIL-4 or rhTNF-alpha alone induced only a weak proliferative response, a synergistic proliferative signal was clearly evident on stimulation of cells with a combination of both cytokines. The stimulatory effect of rhTNF-alpha is mediated predominantly by the 55-kDa TNF receptor because the agonistic monoclonal antibody htr-9 and the Trp32 Thr86 TNF-alpha mutant protein specific for this receptor type produced similar results to rhTNF-alpha. In contrast, the Asn143 Arg145 TNF-alpha mutant protein specific for the 75-kDa TNF receptor produced only minimal proliferation of M-O7e cells. Using RT-PCR, we found that rhTNF-alpha rapidly and strongly induced granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA production, while rhIL-4 was a slow and less efficient inducer of GM-CSF mRNA. However, there was little evidence of the TNF-alpha/IL-4 combination acting synergistically on GM-CSF mRNA production as the levels of GM-CSF mRNA increased only marginally compared with IL-4 or TNF-alpha alone. Thus, the observed synergistic effect of TNF-alpha/IL-4 costimulation of M-O7e cells seems to be mediated via induction of GM-CSF secretion rather than an enhanced production of GM-CSF mRNA. Higher levels of GM-CSF were detectable in supernatants of cells treated with both rhIL-4 and rhTNF-alpha than in cells stimulated with either cytokine alone. Furthermore, addition of a neutralising antibody against GM-CSF abrogated the observed synergistic effect of rhIL-4 and rhTNF-alpha treatment, indicating that the rhIL-4/TNF-alpha combination acts to significantly increase GM-CSF release which then acts in an autocrine manner to enhance the proliferation of M-O7e cells.

Antibodies, Monoclonal↗
PubMed1996

The biological properties, assay, and standardization of interferon-alpha: a need for a WHO collaborative study.

Interferon-alpha (IFN-alpha) exists as a range of closely related, biologically active proteins and has been the subject of extensive research and clinical investigation. Standardization of IFN-alpha and the uniform reporting of IFN-alpha activity in International Units (IU) is critical to preclinical research and the clinical development of IFN-alpha products as therapeutic agents. Currently, several different IFN-alpha-containing reference preparations, established as World Health Organization (WHO) International Standards (IS) for particular IFN-alpha proteins (mixtures or single molecular species) are available for assay calibration. Nevertheless, the heterogeneous nature of IFN-alpha has raised standardization issues relating to the activity of individual IFN-alpha proteins, hence-forth termed subtypes, in the various biologic assays used for determining IFN-alpha levels. These issues include the question of parallelism of dose-response curves among particular IFN-alpha subtypes and different, naturally produced IFN-alpha subtype mixtures, for example, leukocyte IFN-alpha, and the applicability of IU of IFN-alpha activity defined by antiviral assays to alternative biologic assays, for example, antiproliferative assays. To address such issues, a WHO Consultative Group on Cytokine Standardization requested that the National Institute for Biological Standards and Control (NIBSC) and the Centre for Biologics Evaluation and Research (CBER) organize an international collaborative study to compare the activities and relative potencies of the several available IFN-alpha preparations, including those derived from human cells containing mixtures of IFN-alpha subtypes and those derived by rDNA methods containing single IFN-alpha subtypes, in different assays. To date, 111 participants in 32 countries have been recruited to the study and have agreed to assay a total of 17 different natural and recombinant IFN-alpha preparations or a defined subset thereof in specific in-house assays. The assay results generated will be statistically analyzed and evaluated to address the stated issues and to assess whether any individual IFN-alpha preparation is suitable to serve as an IS for all IFN-alpha preparations or whether more than one IS will be needed for this purpose.

Animals↗
PubMed1996

Effect of cyclo-oxygenase inhibitors and modulators of cyclic AMP formation on lipopolysaccharide-induced neutrophil infiltration in mouse lung.

1. The adult respiratory distress syndrome (ARDS) is an acute lung inflammation developed after direct or indirect contact with pathogenic agents. In the present study, a mouse model was developed to mimic this condition using aerosolized bacterial lipopolysaccharide (LPS) and to investigate the mechanisms involved in the lung inflammatory response. 2. Inhalation of LPS led to a time and dose-dependent increase in tumour necrosis factor-alpha (TNF-alpha) production and neutrophil recruitment into the bronchoalveolar lavage fluid (BALF) of Balb/c mice. Under the same conditions, neutrophil infiltration was also found in the BALF of the LPS-sensitive mouse strain C3H/HeN, but was absent in the LPS-resistant strain C3H/HeJ. Intranasal administration of murine recombinant TNF-alpha also triggered neutrophil recruitment. 3. One hour after inhalation of LPS, half of the maximal level of TNF-alpha was measured in the BALF, but only a few neutrophils were detected at this time. The peak TNF-alpha concentration was reached at 3 h, when the neutrophil amount started to increase. At 24 h, maximal neutrophil number was found in the BALF and TNF-alpha was no longer present. 4. Pretreatment of mice under different experimental conditions demonstrated that: (a) cycloheximide almost completely blocks both neutrophil recruitment and TNF-alpha production; (b) anti TNF-alpha antibodies block neutrophil recruitment; (c) indomethacin or aspirin enhance by two fold neutrophil recruitment; (d) indomethacin significantly increases TNF-alpha production 1 h after inhalation of LPS; (e) dibutyryl cyclic AMP and prostaglandin E2 (PGE2) block both neutrophil recruitment and TNF-alpha production. 5. It is concluded that aerosolized LPS in mice triggers an acute lung inflammation which can be used as a potential model of inhalational ARDS and that, strategies leading to the elevation of cyclic AMP levels in vivo can be effective in modulating LPS-induced TNF-alpha synthesis and neutrophil recruitment.

Administration, Inhalation↗
PubMed1996

Activation of the tumor necrosis factor-alpha system in the liver in chronic hepatitis B virus infection.

To determine the status of the tumor necrosis factor-alpha (TNFalpha) system in the liver in chronic hepatitis B virus (HBV) infection, hepatic expression of TNFalpha, its two receptors (TNFR-A, TNFR-B), HLA class I antigens (HLA-I), and HBV core antigen (HBcAg) were studied by immunohistochemistry in 24 patients with chronic HBV infection. TNFalpha was detected exclusively in the infiltrating mononuclear cells (MNC) in 19 of 24 patients. The expression of TNFalpha in infiltrating MNC correlated with serum markers of HBV replication and liver histology. TNFR were detected in hepatocytes, sinusoidal cells, and infiltrating MNC. The expression of TNFR correlated with liver histology (p < 0.01) but had no bearing on viral replication. There was a parallel expression of TNFalpha and TNFR (p < 0.01). Hepatocytic expression of HLA-I was increased, and this was related to liver histology but not with TNF alpha nor TNFR. These data indicate that the TNFalpha system is activated in the liver in chronic HBV infection.

Adult↗
PubMed1995

Evaluation of assay designs for assays using microtitre plates: results of a study of in vitro bioassays and immunoassays for tumour necrosis factor (TNF).

Biological assays for tumour necrosis factor (TNF) are primarily based on its cytotoxic effect in tumour cell lines, and many of these bioassays are carried out using microtitre plates. Many immunoassays for TNF also routinely use microtitre plates. Data from an international collaborative study, carried out by twenty participants in nine countries, each of whom evaluated seven different ampouled preparations of human tumour necrosis factor alpha (hTNF-alpha), one ampouled preparation of human tumour necrosis beta (hTNF-beta) and one ampouled preparation of mouse tumour necrosis factor alpha (mTNF-alpha) provided a unique opportunity for a broadly based evaluation and comparison of assay designs and results. The results of this evaluation can be applied to a wide range of in vitro assays based on cell cytotoxicity or proliferation. The results of this evaluation indicated that although it is difficult to achieve control of all factors which contribute to the variability of assay responses, assays may be designed to provide measures of the variation due to some factors and to improve reliability of estimates of relative potency.

Animals↗
PubMed1995

Tumor necrosis factor mediates the protective effect of Freund's adjuvant against autoimmune diabetes in BB rats.

In previous studies we reported that a single injection of complete Freund's adjuvant (CFA) in early life inhibits the development of autoimmune diabetes in BB diabetes-prone (DP) rats, and that CFA upregulates tumor necrosis factor-alpha (TNF alpha) production by macrophages of DP rats. In this study, we asked if CFA-induced prevention of diabetes in DP rats might be mediated by TNF alpha. Chronic intraperitoneal injection of TNF alpha, 20 micrograms daily from age 50 to 110 days, significantly decreased diabetes incidence in DP rats from 83% (15 of 18) to 37% (seven of 19) at age 110 days. Similarly, a single intraperitoneal injection of CFA, 100 microliters at age 26 days, significantly decreased diabetes incidence from 80% (16 of 20) to 50% (10 of 20) at age 110 days. Prevention by either TNF alpha or CFA was associated with decreased insulitis and preservation of islet beta-cells. By contrast, treatment of DP rats with CFA, plus antiserum to TNF alpha three times a week from age 26 to 110 days, obviated CFA-induced protection against beta-cell destructive insulitis and diabetes. Thus, diabetes incidence was 75% (18 of 24) in DP rats treated with CFA plus anti-TNF alpha antiserum, similar to that in untreated DP rats (80%), but only 44% (eight of 18) in DP rats treated with CFA plus control serum, similar to that in DP rats with CFA alone (50%). These results suggest that TNF alpha may be a mediator of the protective effects of CFA against autoimmune diabetes development in BB rats.

Animals↗
PubMed1995

Modulation of antibody-mediated glomerular injury in vivo by IL-1ra, soluble IL-1 receptor, and soluble TNF receptor.

The severity of glomerular injury in the heterologous phase of NTN is dependent on proinflammatory cytokines including TNF alpha and IL-1 beta, and can be enhanced by LPS. We have previously shown that passive immunization against IL-1 beta and TNF partially abrogated the LPS effect in this model. In the present work, we have assessed the effects on glomerular injury of blocking and binding of IL-1 to its receptor by rh IL-1 receptor antagonist (IL-1ra) and by neutralizing IL-1 and TNF with rm soluble IL-1 receptor type1 (sIL-1Rt1) and rh sTNF receptor (sTNFr p55), respectively. Pretreatment with either IL-1ra, sIL-1Rt1, or sTNFr partially abrogated the effects of LPS and reduced albumin excretion from 45 +/- 8, 66 +/- 9, and 101 +/- 17 mg/24 hr at 13 +/- 4 (P < 0.02), 14 +/- 4 (P < 0.001), and 21 +/- 7 mg/24 hr (P < 0.001), respectively. Similarly, these inhibitors reduced the prevalence of glomerular capillary thrombi and the intensity of glomerular neutrophil infiltration. Glomerular thrombosis was reduced from 18 +/- 3%, 28 +/- 5%, and 25 +/- 7% to 3 +/- 2% (P < 0.002), 6 +/- 2% (P < 0.001), and 3 +/- 2 (P < 0.001), respectively, and glomerular neutrophil infiltration was reduced from 46 +/- 3, 54 +/- 2, 59 +/- 8 to 19 +/- 2 (P < 0.001), 25 +/- 2 (P < 0.001), and 28 +/- 2 neutrophils/50 glomeruli in section, respectively. Coadministration of both soluble receptors of IL-1 and TNF caused a further decrease in glomerular injury. The protective effect was also noticed at four hours after induction of nephritis, and even when these inhibitors were administered after the LPS injection and at the same time of induction of nephritis. All three treatments reduced circulating TNF concentration (down to 20%, 34%, and 0%, respectively) but without detectable glomerular TNF gene expression. Glomerular IL-1 beta mRNA levels were also reduced by 41%, 53%, and 67%, respectively, when assessed by densitometric analysis of Northern blots. In contrast, the glomerular expression of IL-1ra was not affected by its exogenous administration but was mildly reduced by sIL-1Rt1 and sTNFr, which demonstrates the potential role for host derived IL-1ra as an endogenous negative feedback mediator in the glomerulus. These results confirm the direct involvement of IL-1 and TNF in LPS-enhanced hNTN and demonstrate the potency of these inhibitors in modulating injury even when administered after LPS and in time of induction of nephritis. They were more specific and effective than passive immunization with polyclonal antibodies, and this demonstrates their potential usefulness in the management of nephritis.

Animals↗
PubMed1995

T cell activation in vivo by dengue virus infection.

It is accepted that T cells play a critical role during virus infections; however, T cell responses in vivo in acute stage of virus infection are not understood. We examined T cell activation in vivo in two volunteers who developed dengue fever in response to vaccination with a candidate live dengue vaccine. Serial plasma collected from the volunteers from day 0 (before infection) to day 17 after infection were examined for levels of soluble interleukin-2 receptor (sIL-2R), soluble CD4 (sCD4), soluble CD8 (sCD8), interleukin-2 (IL-2) and interferon gamma (INF gamma). Elevation of the levels of sIL-2R, IFN gamma, sCD4 and IL-2 became obvious during the period of viremia and was followed by a later increase in the level of sCD8. The levels of IFN gamma and sIL-2R declined after the end of the period of viremia. These results indicate that i. T cells are activated in vivo by dengue virus infection ii. activation of CD4+ T cells occurs during the period of viremia iii. activation of CD8+ T cells follows CD4+ T cell activation. These results suggest that activation of T cells in vivo may contribute to controlling acute dengue virus infections.

Adult↗
PubMed1994

Tumor necrosis factor (TNF)-induced protein phosphorylation in a human rhabdomyosarcoma cell line is mediated by 60-kD TNF receptors (TR60).

In the present study, we used a cloned derivative, KYM-1D4, of the human rhabdomyosarcoma cell line, KYM-1, known to express high numbers of the two tumor necrosis factor (TNF) receptors, TR60 and TR80, and to be highly sensitive to TNF alpha-mediated cytotoxicity/antiproliferation, to investigate the role of TR60 and TR80 in protein phosphorylation. Using permeabilized KYM-1D4 cells, it was found that TNF alpha strongly induced phosphorylation of proteins of molecular weight 80, 65, 58, 42, and 30 kD. Addition of a monoclonal antibody (MoAb) against TR60 was shown to induce cytotoxicity/antiproliferation in KYM-1D4 cells and the same pattern of protein phosphorylation as TNF alpha, whereas addition of an MoAb against TR80 was both noncytotoxic and ineffective in inducing protein phosphorylation. In contrast, in a highly TNF alpha-resistant KYM-1-derived cell line, 37B8R, no protein phosphorylation was induced with either TNF alpha or the agonistic anti-TR60 MoAb. However, when 37B8R was allowed to revert to partial TNF sensitivity by culture in the absence of TNF alpha, the resultant cell line, 37B8S, was found to regain inducibility of protein phosphorylation by TNF alpha. These results indicate that expression of functional TR60 in KYM-1-related cell lines is principally involved in TNF-mediated cytotoxicity/antiproliferation and is necessary for the induction of protein phosphorylation. Nevertheless, the latter, although apparently strongly associated with cytotoxicity, was probably involved in protective mechanisms because protein kinase C inhibitors that inhibited TNF alpha and anti-TR60-induced phosphorylation increased the cytotoxic/antiproliferative response to these mediators.

Humans↗
PubMed1994

International collaborative study of the candidate international standards for human tumour necrosis factors alpha (hTNF-alpha) and beta (hTNF-beta) and for murine tumour necrosis factor alpha (mTNF-alpha).

Four ampouled preparations of human tumour necrosis factor alpha (hTNF-alpha), one ampoule of human tumour necrosis factor beta (hTNF-beta) and one ampoule of mouse tumour necrosis factor alpha (mTNF-alpha) were evaluated by 20 laboratories in nine countries for their suitability to serve as international standards for these materials. A further three preparations of recombinant hTNF-alpha were included in the study so that hTNF-alpha preparations from different sources and with various structures could be compared. The preparations were assayed using in vitro bioassays and immunoassays. On the basis of the results reported here, with the agreement of participants in the study and with the authorisation of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO), the preparation of hTNF-alpha in ampoules designated 87/650 was established as the international standard for hTNF-alpha with a defined potency of 40,000 international units per ampoule. Estimates relative to hTNF-alpha for both hTNF-beta and mTNF-alpha showed a substantial inter-laboratory variability in cytotoxic activity indicating that no preparations of hTNF-alpha would be suitable as a reference standard for either hTNF-beta or mTNF-alpha. However, given the current need for reference preparations for these materials, the ampouled preparations of hTNF-beta (87/640) and mTNF-alpha (88/532) were assigned potencies in arbitrary units and are available as reference reagents.

Animals↗