Production of tumor necrosis factor/cachectin by human B cell lines and tonsillar B cells

Cytokine production by human B cells: role in health and autoimmune disease

B cells are classically considered solely as antibody-producing cells driving humoral immune responses to foreign antigens in infections and vaccinations as well as self-antigens in pathological settings such as autoimmunity. However, it has now become clear that B cells can also secrete a vast array of cytokines, which influence both pro- and anti-inflammatory immune responses. Indeed, similarly to T cells, there is significant heterogeneity in cytokine-driven responses by B cells, ranging from the production of pro-inflammatory effector cytokines such as IL-6, through to the release of immunosuppressive cytokines such as IL-10. In this review, focusing on human B cells, we summarize the key findings that have revealed that cytokine-producing B cell subsets have critical functions in healthy immune responses and contribute to the pathophysiology of autoimmune diseases.

Lymphocytes from B-acute lymphoblastic leukemia patients present differential regulation of the adenosinergic axis depending on risk stratification

PURPOSE

Although risk-stratified chemotherapy regimens improve B-cell acute lymphoblastic leukemia (B-ALL) clinical outcome, relapse occurs in a significant number of cases. The identification of new therapeutic targets as well as prognostic and diagnostic biomarkers can improve B-ALL patients' clinical outcomes. Purinergic signaling is an important pathway in cancer progression, however the expression of ectonucleotidases and their impact on immune cells in B-ALL lacks exploration. We aimed to analyze the expression of ectonucleotidases in B-ALL patients' lymphocyte subpopulations.

METHODS

Peripheral blood samples from 15 patients diagnosed with B-ALL were analyzed. Flow cytometry was used to analyze cellularity, expression level of CD38, CD39, and CD73, and frequency of [Formula: see text], and [Formula: see text] in lymphocyte subpopulations. Plasma was used for cytokines (by CBA kit) and adenine nucleosides/nucleotides detection (by HPLC).

RESULTS

Comparing B-ALL patients to health donors, we observed an increase of CD4 + and CD8 + T-cells. In addition, a decrease in CD38 expression in B and Treg subpopulations and an increase in CD39⁺ CD73⁺  frequency in Breg and CD8+ T-cells. Analyzing cytokines and adenine nucleosides/nucleotides, we found a decrease in TNF, IL-1β, and ADO concentrations, together with an increase in AMP in B-ALL patients' plasma.

CONCLUSION

As immunomodulators, the expression of ectonucleotidases might be associated with activation states, as well as the abundance of different cellular subsets. We observed a pro-tumor immunity expression profile in B-ALL patients at diagnosis, being associated with cell exhaustion and immune evasion in B-ALL.

Tfh cells with NLRP3 inflammasome activation are essential for high-affinity antibody generation, germinal centre formation and autoimmunity

OBJECTIVE

NLRP3 inflammasome regulates T cell responses. This study examined the roles of NLRP3 inflammasome activation in the regulation of T follicular helper (Tfh) cells during humoral response to T dependent antigens and in systemic lupus erythematosus (SLE).

METHODS

NLRP3 inflammasome activation of Tfh cells was studied in B6, MRL/lpr and NZM2328 mice and in SLE patients and healthy controls using a fluorescence-labelled caspase-1 inhibitor probe. MCC950, a selective inhibitor of NLRP3, was used to investigate the relation between NLRP3 inflammasome activation and germinal centre (GC) reaction, Ab responses to immunisation, and autoantibody production.

RESULTS

NLRP3 inflammasome activation in Tfh cells after immunisation was identified in B6 mice. MCC950 inhibited humoral responses to sheep red blood cell and NP-CGG with reduction of the GC reaction. B6 mice with lymphoid cell-specific deletion of NLRP3 or Casp1 mounted suboptimal humoral responses with impaired GC formation and defective affinity maturation. In MRL/lpr and NZM2328 mice, inhibition of NLRP3 activation suppressed NLRP3 activated Tfh cell expansion as well as attenuated lupus-like phenotypes. Tfh cells with activated NLRP3 inflammasome exhibited increased expression of molecules for Tfh cell function and differentiation, and had greater ability to activate B cells. In SLE patients, disease activity was positively correlated with an increase in the activated NLRP3⁺ Tfh population and this population was markedly reduced in response to therapy.

CONCLUSIONS

The activation of NLRP3 inflammasome in Tfh cells is an integral part of responses to immunisation. The activated NLRP3⁺ Tfh population is essential for optimal humoral responses, GC formation and autoimmunity.

Complement regulation in tenocytes under the influence of leukocytes in an indirect co-culture model

INTRODUCTION

The present in vitro study was undertaken to learn about the effects of leukocytes on tenocytes in respect to complement regulation simulating an inflammatory scenario of the traumatized tissue.

METHODS

Human hamstring tendon-derived tenocyte monolayers were co-cultured indirectly with human leukocytes (either Peripheral Blood Mononuclear Cells [PBMCs] or neutrophils) using a transwell system with/without (+ /_wo) 10 ng/ml tumor necrosis factor α (TNFα) for 4 and 24 h. Tenocyte and leukocyte cell survival was assessed by live-dead assay. Tenocyte gene expression of TNFα, the anaphylatoxin receptor C5aR and the cytoprotective complement regulatory proteins (CRP) CD46, CD55 and CD59 was monitored using qPCR. TNFα was detected in the culture supernatants using ELISA.

RESULTS

C5aR gene expression was significantly induced by TNFα after 4 h, but impaired in the presence of leukocytes + TNFα after 24 h. At 4 h, PBMCs activated by TNFα induced the CRP CD46 gene expression. However, CD55 was significantly suppressed after 24 h by neutrophils + /_woTNFα. Leukocytes activated by TNFα decreased also significantly the gene expression of the more downstream acting CRP CD59 after 4 h. TNFα gene expression and ELISA analysis revealed an amplified TNFα expression/release in tenocyte co-cultures with PBMC + /_woTNFα, probably contributing to complement regulation.

CONCLUSION

TNFα might represent a crucial soluble mediator exerting diverse time-dependent effects on tenocyte complement regulation.

A Comprehensive Phenotypic and Functional Immune Analysis Unravels Circulating Anti-Phospholipase A2 Receptor Antibody Secreting Cells in Membranous Nephropathy Patients

Introduction

Primary membranous nephropathy (MN) is characterized by the presence of antipodocyte antibodies, but studies describing phenotypic and functional abnormalities in circulating lymphocytes are limited.

Methods

We analyzed 68 different B- and T-cell subsets using flow cytometry in 30 MN patients (before initiating immunosuppression) compared with 31 patients with non–immune-mediated chronic kidney disease (CKD) and 12 healthy individuals. We also measured 19 serum cytokines in MN patients and in healthy controls. Lastly, we quantified the ex vivo production of phospholipase A2 receptor (PLA2R)-specific IgG by plasmablasts (measuring antibodies in culture supernatants and by the newly developed FluoroSpot assay [AutoImmun Diagnostika, Strasberg, Germany]) and assessed the circulating antibody repertoire by phage immunoprecipitation sequencing (PhIP-Seq).

Results

After adjusting for multiple testing, plasma cells and regulatory B cells (B_REG) were significantly higher (P < 0.05) in MN patients compared with both control groups. The percentages of circulating plasma cells correlated with serum anti-PLA2R antibody levels (P = 0.042) and were associated with disease activity. Ex vivo–expanded PLA2R-specific IgG-producing plasmablasts generated from circulating PLA2R-specific memory B cells (mBCs) correlated with serum anti-PLA2R IgG antibodies (P < 0.001) in MN patients. Tumor necrosis factor-α (TNF-α) was the only significantly increased cytokine in MN patients (P < 0.05), whereas there was no significant difference across study groups in the autoantibody and antiviral antibody repertoire.

Conclusion

This extensive phenotypic and functional immune characterization shows that autoreactive plasma cells are present in the circulation of MN patients, providing a new therapeutic target and a candidate biomarker of disease activity.

Constitutive and inducible in vivo protein-DNA interactions at the tumor necrosis factor-alpha promoter in primary human T lymphocytes

Tumor necrosis factor-alpha (TNF-alpha) is a key cytokine of lymphocytes with major regulatory functions in immunomodulation, chronic inflammation, and septic shock. However, only limited information on TNF promoter regulation in vivo in primary lymphocytes is available. To determine and compare protein-DNA interactions at the native TNF locus in primary lymphocytes, we analyzed the human TNF-alpha promoter by ligation-mediated polymerase chain reaction (LM-PCR) techniques. Accordingly, primary CD4+ T lymphocytes from peripheral blood were cultured in the presence of various stimuli and analyzed by LM-PCR. Inducible in vivo protein-DNA interactions at the TNF promoter were detected between -120 and -70 bp of the human TNF promoter relative to the transcriptional start site. This area includes binding sites for transcription factors such as ETS-1, NFAT, ATF-2/c-jun, SP-1/Egr-1, and NF-kappaB. In contrast, no protein-DNA interactions were observed at various binding sites with reported regulatory function in tumor cell lines such as the k2 element, the NFAT site at -160, the AP1 site at -50, and the SP1 site at -65. Additional mutagenesis and transfection studies demonstrated that NF-kappaB and CREB/AP-1 are important regulators of inducible TNF promoter activity in primary human T lymphocytes. These results provide novel insights into the complex regulation of TNF gene transcription in primary T lymphocytes in vivo by constitutive and inducible protein-DNA interactions that appear to be at least partially different compared to previously characterized tumor cell lines.

Regulation of endotoxin mitogenicity in murine spleen cells by tumor necrosis factor α

In the present study the role of tumor necrosis factor α (TNFα) in endotoxin-induced mitogenicity of mouse spleen cells was examined. TNFα was found to enhance endotoxin-induced proliferation of spleen cells. However, in the absence of endotoxin, tumor necrosis factor treatment was without effect. An antiserum against TNFα completely abolished the mitogenic effect of endotoxin in spleen cell cultures. This inhibition was reversed by exogenously added TNFα. The TNFα production in spleen cell cultures reached a maximum after 6 h. When the antiserum was added to cultures at various time intervals following endotoxin addition, maximal inhibition was observed at a time point 6 h after the start. These data suggest that TNFα has a function in endotoxin-induced mitogenicity of murine spleen cells.

Mucosal Inducible NO Synthase-Producing IgA+ Plasma Cells in Helicobacter pylori-Infected Patients

The mucosal immune system is relevant for homeostasis, immunity, and also pathological conditions in the gastrointestinal tract. Inducible NO synthase (iNOS)-dependent production of NO is one of the factors linked to both antimicrobial immunity and pathological conditions. Upregulation of iNOS has been observed in human Helicobacter pylori infection, but the cellular sources of iNOS are ill defined. Key differences in regulation of iNOS expression impair the translation from mouse models to human medicine. To characterize mucosal iNOS-producing leukocytes, biopsy specimens from H. pylori-infected patients, controls, and participants of a vaccination trial were analyzed by immunohistochemistry, along with flow cytometric analyses of lymphocytes for iNOS expression and activity. We newly identified mucosal IgA-producing plasma cells (PCs) as one major iNOS(+) cell population in H. pylori-infected patients and confirmed intracellular NO production. Because we did not detect iNOS(+) PCs in three distinct infectious diseases, this is not a general feature of mucosal PCs under conditions of infection. Furthermore, numbers of mucosal iNOS(+) PCs were elevated in individuals who had cleared experimental H. pylori infection compared with those who had not. Thus, IgA(+) PCs expressing iNOS are described for the first time, to our knowledge, in humans. iNOS(+) PCs are induced in the course of human H. pylori infection, and their abundance seems to correlate with the clinical course of the infection.

Expansion of Activated Peripheral Blood Memory B Cells in Rheumatoid Arthritis, Impact of B Cell Depletion Therapy, and Biomarkers of Response

Although B cell depletion therapy (BCDT) is effective in a subset of rheumatoid arthritis (RA) patients, both mechanisms and biomarkers of response are poorly defined. Here we characterized abnormalities in B cell populations in RA and the impact of BCDT in order to elucidate B cell roles in the disease and response biomarkers. In active RA patients both CD27+IgD- switched memory (SM) and CD27-IgD- double negative memory (DN) peripheral blood B cells contained significantly higher fractions of CD95+ and CD21- activated cells compared to healthy controls. After BCD the predominant B cell populations were memory, and residual memory B cells displayed a high fraction of CD21- and CD95+ compared to pre-depletion indicating some resistance of these activated populations to anti-CD20. The residual memory populations also expressed more Ki-67 compared to pre-treatment, suggesting homeostatic proliferation in the B cell depleted state. Biomarkers of clinical response included lower CD95+ activated memory B cells at depletion time points and a higher ratio of transitional B cells to memory at reconstitution. B cell function in terms of cytokine secretion was dependent on B cell subset and changed with BCD. Thus, SM B cells produced pro-inflammatory (TNF) over regulatory (IL10) cytokines as compared to naïve/transitional. Notably, B cell TNF production decreased after BCDT and reconstitution compared to untreated RA. Our results support the hypothesis that the clinical and immunological outcome of BCDT depends on the relative balance of protective and pathogenic B cell subsets established after B cell depletion and repopulation.

The immune potential and immunopathology of cytokine-producing B cell subsets: a comprehensive review

B lymphocytes are generally recognized for their potential to mediate humoral immunity by producing different antibody isotypes and being involved in opsonization and complement fixation. Nevertheless, the non-classical, antibody-independent immune potential of B cell subsets has attracted much attention especially in the past decade. These B cells can release a broad variety of cytokines (such as IL-2, IL-4, IL-6, IL-10, IL-17, IFN-α, IFN-γ, TNF-α, TGF-β, LT), and can be classified into distinct subsets depending on the particular cytokine profile, thus emerging the concept of cytokine-producing B cell subsets. Although there is still controversy surrounding the key cell surface markers, intracellular factors and cellular origins of cytokine-producing B cell subsets, accumulating evidence indicates that these B cells are endowed with great potential to regulate both innate and adaptive arms of immune system though releasing cytokines. On the one hand, they promote immune responses through mounting Th1/Th2/Th17 and neutrophil response, inducing DC maturation and formation of lymphoid structures, increasing NK cell and macrophage activation, enhancing development of themselves and sustaining antibody production. On the other hand, they can negatively regulate immune responses by suppressing Th cell responses, inhibiting Tr1 cell and Foxp3(+) Treg differentiation, impairing APC function and pro-inflammatory cytokine release by monocytes, and inducing CD8(+) T cell anergy and CD4(+) T cell apoptosis. Therefore, cytokine-producing B cell subsets have multifunctional functions in health and diseases, playing pathologic as well as protective roles in autoimmunity, infection, allergy, and even malignancy. In this review, we revisit the history of discovering cytokine-producing B cells, describe the identification of cytokine-producing B cell subsets, introduce the origins of cytokine-producing B cell subsets as well as molecular and cellular mechanisms for their differentiation, and summarize the recent progress made toward understanding the unexpectedly complex and potentially opposing roles of cytokine-producing B cells in immunological disorders.

TNF-α expression in tumor cells as a novel prognostic marker for diffuse large B-cell lymphoma, not otherwise specified

Several cytokines promote malignant cell growth and are therefore believed to contribute to disease aggressiveness. The cytokine tumor necrosis factor-α (TNF-α) acts as a tumor-promoting factor and has been linked to all tumorigenic stages in many cancers. Here, we evaluated 62 lymphoma tissue specimens from patients having diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS) by immunostaining with anti-TNF-α antibody. Cytoplasmic TNF-α reactivity in ≥20% of the tumor cells was considered positive. Our results demonstrated that tumor specimens from DLBCL, NOS patients could be divided into 2 types-TNF-α positive (38 cases, 61%) and TNF-α negative (24 cases, 39%)--and that TNF-α positivity in DLBCL, NOS was correlated with poorer overall survival (OS; P=0.0005, log rank test) and progression-free survival (PFS; P=0.0330, log rank test) compared with TNF-α negativity. Cox regression analysis showed that TNF-α expression was a significant prognostic factor for OS (P<0.0001) and PFS (P=0.0323). Regarding OS and PFS, multivariate analysis showed that TNF-α expression in tumor cells was an independent prognostic factor for the International Prognostic Index (IPI). Therefore, TNF-α-positive DLBCL, NOS may constitute a unique subtype of DLBCL, NOS with an aggressive clinical course. The addition of TNF-α expression to the IPI may significantly improve the predictive prognostic value. The therapeutic strategy of DLBCL, NOS patients should be based on correct prognosis; therefore, patients with poor prognoses could be more accurately detected by evaluating both TNF-α expression levels and the IPI.

Epigenetic control of cytokine gene expression: regulation of the TNF/LT locus and T helper cell differentiation

Epigenetics encompasses transient and heritable modifications to DNA and nucleosomes in the native chromatin context. For example, enzymatic addition of chemical moieties to the N-terminal "tails" of histones, particularly acetylation and methylation of lysine residues in the histone tails of H3 and H4, plays a key role in regulation of gene transcription. The modified histones, which are physically associated with gene regulatory regions that typically occur within conserved noncoding sequences, play a functional role in active, poised, or repressed gene transcription. The "histone code" defined by these modifications, along with the chromatin-binding acetylases, deacetylases, methylases, demethylases, and other enzymes that direct modifications resulting in specific patterns of histone modification, shows considerable evolutionary conservation from yeast to humans. Direct modifications at the DNA level, such as cytosine methylation at CpG motifs that represses promoter activity, are another highly conserved epigenetic mechanism of gene regulation. Furthermore, epigenetic modifications at the nucleosome or DNA level can also be coupled with higher-order intra- or interchromosomal interactions that influence the location of regulatory elements and that can place them in an environment of specific nucleoprotein complexes associated with transcription. In the mammalian immune system, epigenetic gene regulation is a crucial mechanism for a range of physiological processes, including the innate host immune response to pathogens and T cell differentiation driven by specific patterns of cytokine gene expression. Here, we will review current findings regarding epigenetic regulation of cytokine genes important in innate and/or adaptive immune responses, with a special focus upon the tumor necrosis factor/lymphotoxin locus and cytokine-driven CD4+ T cell differentiation into the Th1, Th2, and Th17 lineages.

Cytokines and effector T cell subsets causing autoimmune CNS disease

Although experimental autoimmune encephalomyelitis (EAE) is limited in its potency to reproduce the entirety of clinical and histopathologic features of multiple sclerosis (MS), this model has been successfully used to prove that MS like autoimmunity in the CNS is orchestrated by autoantigen specific T cells. EAE was also very useful to refute the idea that IFN-γ producing T helper type 1 (Th1) cells were the sole players within the pathogenic T cell response. Rather, "new" T cell lineages such as IL-17 producing Th17 cells or IL-9 producing Th9 cells have been first discovered in the context of EAE. Here, we will summarize new concepts of early and late T cell plasticity and the cytokine network that shapes T helper cell responses and lesion development in CNS specific autoimmunity.

Conventional B2 B cell depletion ameliorates whereas its adoptive transfer aggravates atherosclerosis

Atherosclerosis is a chronic inflammatory arterial disease characterized by focal accumulation of lipid and inflammatory cells. It is the number one cause of deaths in the Western world because of its complications of heart attacks and strokes. Statins are effective in only approximately one third of patients, underscoring the urgent need for additional therapies. B cells that accumulate in atherosclerotic lesions and the aortic adventitia of humans and mice are considered to protect against atherosclerosis development. Unexpectedly, we found that selective B cell depletion in apolipoprotein E-deficient (ApoE(-/-)) mice using a well-characterized mAb to mouse CD20 reduced atherosclerosis development and progression without affecting the hyperlipidemia imposed by a high-fat diet. Adoptive transfer of 5 × 10(6) or 5 × 10(7) conventional B2 B cells but not 5 × 10(6) B1 B cells to a lymphocyte-deficient ApoE(-/-) Rag-2(-/-) common cytokine receptor γ-chain-deficient mouse that was fed a high-fat diet augmented atherosclerosis by 72%. Transfer of 5 × 10(6) B2 B cells to an ApoE(-/-) mouse deficient only in B cells aggravated atherosclerosis by >300%. Our findings provide compelling evidence for the hitherto unrecognized proatherogenic role of conventional B2 cells. The data indicate that B2 cells can potently promote atherosclerosis development entirely on their own in the total absence of all other lymphocyte populations. Additionally, these B2 cells can also significantly augment atherosclerosis development in the presence of T cells and all other lymphocyte populations. Our findings raise the prospect of B cell depletion as a therapeutic approach to inhibit atherosclerosis development and progression in humans.

Mast cell stabilization improves survival by preventing apoptosis in sepsis

Inhibiting single cytokines produced modest effects in clinical trials, in part because the cytokines were not specific for sepsis, and sepsis may require cellular strategies. Previous studies reported that mast cells (MCs) fight infections in early sepsis. In this study, we report that MC stabilizers restrain serum TNF levels and improve survival in wild-type but not in MC-deficient mice. Yet, MC depletion in knockout mice attenuates serum TNF but does not improve survival in sepsis. Serum HMGB1 was the only factor correlating with survival. MC stabilizers inhibit systemic HMGB1 levels and rescue mice from established peritonitis. MC stabilizers fail to inhibit HMGB1 secretion from macrophages, but they prevent apoptosis and caspase-3 activation in sepsis. These results suggest that MC stabilization provides therapeutic benefits in sepsis by inhibiting extracellular release of HMGB1 from apoptotic cells. Our study provides the first evidence that MCs have major immunological implications regulating cell death in sepsis and represent a pharmacological target for infectious disorders in a clinically realistic time frame.

Transcriptional control of the TNF gene

The cytokine TNF is a critical mediator of immune and inflammatory responses. The TNF gene is an immediate early gene, rapidly transcribed in a variety of cell types following exposure to a broad range of pathogens and signals of inflammation and stress. Regulation of TNF gene expression at the transcriptional level is cell type- and stimulus-specific, involving the recruitment of distinct sets of transcription factors to a compact and modular promoter region. In this review, we describe our current understanding of the mechanisms through which TNF transcription is specifically activated by a variety of extracellular stimuli in multiple cell types, including T cells, B cells, macrophages, mast cells, dendritic cells, and fibroblasts. We discuss the role of nuclear factor of activated T cells and other transcription factors and coactivators in enhanceosome formation, as well as the contradictory evidence for a role for nuclear factor kappaB as a classical activator of the TNF gene. We describe the impact of evolutionarily conserved cis-regulatory DNA motifs in the TNF locus upon TNF gene transcription, in contrast to the neutral effect of single nucleotide polymorphisms. We also assess the regulatory role of chromatin organization, epigenetic modifications, and long-range chromosomal interactions at the TNF locus.

Role of TNF-α in human female reproduction

TNF-α is a highly versatile cytokine, playing an important role in both apoptosis and inflammation, which is central to reproduction. It belongs to the Th1 type of cytokines. Thus, TNF-α is a proinflammatory cytokine and is involved during follicle development and ovulation, corpus luteum formation and regression and cyclic endometrium function. It has been postulated to be detrimental to the survival of the conceptus due to apoptosis of human primary villous trophoblast cells, leading to miscarriage. However, TNF-α may have a dual role in early pregnancy. Hormonally regulated uterine TNF-α in the mother is probably essential for trophoblast cell invasion, while increased production of TNF-α by maternal macrophages may facilitate labor. The current knowledge on the role of TNF-α and its receptors in the female reproduction is described in this review.

Biologic and clinical significance of cytokine production in B-cell malignancies

Cytokines are a group of polypeptide hormones endowed with pleiotropic biological properties. Normal B lymphocytes produce a number of these factors that subserve important regulatory functions in the combined processes of proliferation and differentiation. Also neoplastic B cells can release cytokines and, simultaneously, respond to the same factors in an autocrine circuit that supports their malignant growth. In addition, tumor cells can make use of the factors released by normal cells, either spontaneously or under the influence of inductive signals from the neoplastic cells. Inappropriate or excessive release of cytokines may have an important role in the pathophysiology of some clinical features. Thus, neutralization of cytokine biologic activity in vivo could be a therapeutic strategy for treatment of human B-cell neoplasias.

Tetraspanins regulate ADAM10-mediated cleavage of TNF-alpha and epidermal growth factor

Several cytokines and growth factors are released by proteolytic cleavage of a membrane-anchored precursor, through the action of ADAM (a disintegrin and metalloprotease) metalloproteases. The activity of these proteases is regulated through largely unknown mechanisms. In this study we show that Ab engagement of several tetraspanins (CD9, CD81, CD82) increases epidermal growth factor and/or TNF-alpha secretion through a mechanism dependent on ADAM10. The effect of anti-tetraspanin mAb on TNF-alpha release is rapid, not relayed by intercellular signaling, and depends on an intact MEK/Erk1/2 pathway. It is also associated with a concentration of ADAM10 in tetraspanin-containing patches. We also show that a large fraction of ADAM10 associates with several tetraspanins, indicating that ADAM10 is a component of the "tetraspanin web." These data show that tetraspanins regulate the activity of ADAM10 toward several substrates, and illustrate how membrane compartmentalization by tetraspanins can control the function of cell surface proteins such as ectoproteases.

Mouse splenic B lymphocyte activation using different activation stimuli induces in vitro splicing of tumor necrosis factor-α nuclear pre-mRNA

The pleiotropic functions of tumor necrosis factor-alpha (TNFalpha) have brought considerable attention in the past decade to its physiological and pathological roles in inflammatory and autoimmune diseases. However, little is known about how the production of TNFalpha is regulated at the transcriptional and translational levels in immune cells such as T and B lymphocytes. Our previous study demonstrated that unspliced "pre-mRNA" of TNFalpha is present in resting T cells. Initiation of splicing of TNFalpha pre-mRNA to mature mRNA requires T cell activation, which is unique and necessary for TNFalpha production when compared to its production in mononuclear phagocytes, including different lineages of macrophages (Mvarphi) and dendritic cells (DC). In this study, we further demonstrate that resting mouse B cells also contain pre-existing TNFalpha mRNA. The physiological process of B cell activation induced by (1) either the cross-linking of the B cell receptor (BCR) or CD40, (2) treatment with LPS, or PMA plus ionomycin, induces TNFalpha mRNA splicing in vitro. The kinetic response of TNFalpha splicing in B cells is much slower when compared to that in activated T cells. Studies using well-known kinase inhibitors demonstrated that MAP kinase kinase (MEK) and protein kinase C (PKC) are required for TNFalpha splicing upon stimulation through the BCR. These studies demonstrate that the production of TNFalpha in activated B cells is regulated differently than in activated T cells, and these differences may allow for the selective inhibition of TNFalpha in various autoimmune diseases depending on the mechanism of action of the selected anti-TNFalpha therapy.

Nicorandil inhibits the release of TNFα from a lymphocyte cell line and peripheral blood lymphocytes

Modulation of cytokine release may be of interest in modulating inflammatory diseases. This study determined whether nicorandil, a potassium channel opener, and nitric oxide (NO) donor could inhibit the release of tumour necrosis factor alpha (TNFalpha) from lymphocytes. Nicorandil significantly and dose-dependently inhibited the TNFalpha release from a human Epstein Barr virus-transformed B lymphocyte cell line (EBV-B) and peripheral blood B and T lymphocytes. The inhibition was reversed by the addition of both potassium channel inhibitor glibenclamide and the guanylyl cyclase inhibitor 1H-(1,2,4) oxadiazolo (4,3) quinoxalin-1-one (ODQ). Other potassium channel openers, pinacidil, or the nicorandil analogue SG-209, however, failed to demonstrate inhibition of TNFalpha release. The NO scavenger haemoglobin was unable to reverse the nicorandil-induced TNFalpha inhibition, but in contrast to this, sodium nitroprusside (SNP) partially inhibited the release, which was reversed by haemoglobin. Nicorandil is able to inhibit TNFalpha release from lymphocytes, which requires the dual modes of both potassium channel opening and the nitrate moiety. Moreover, NO donation mechanism appears to be more dominant in the nicorandil inhibitory activity in lymphocytes.The dual mechanism involved in the inhibition of this cytokines may represent a novel therapeutical approach in the modulation of inflammatory disease.

Involution of bursa cloacalis (Fabricii) and thymus in Cyclosporin A-treated chickens

Fifty-day-old Arbor Acres chickens received a daily oral dose of 30 mg/kg Cyclosporin A for 21 consecutive days. This treatment induced the striking morphological changes in the bursa cloacalis (Fabricii). The number of bursal follicles did not change, but they were markedly decreased in size. The pars lymphoreticularis was collapsed and contained smaller accumulations of lymphocytes. The pars lymphoepithelialis was almost totally devoid of lymphocytes and it was composed of an empty network of epithelial cells. Interfollicular epithelium, follicle-associated epithelium, basement-membrane-associated epithelium and bursal epithelial cytoreticulum were not changed. The thymus also displayed substantial structural changes, whereby the thymic medulla was strongly reduced in size.

Oligodeoxynucleotides containing CpG motifs induce low levels of TNF-alpha in human B lymphocytes: possible adjuvants for Th1 responses

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) represent potential adjuvants for specific immunotherapy of type I allergies because they foster Th1-like immune responses. However, previous work has shown that CpG-ODN induce systemically active levels of TNF-alpha in murine macrophages. The goal of the present study was to evaluate the release of TNF-alpha in human cells by a CpG-ODN proven to induce Th1 immune responses in cells from atopic individuals and in mice. CpG-ODN induced TNF-alpha in cells from atopic and healthy individuals. However, the amounts were low, as determined by comparison with commonly used Ags. Intracellular cytokine staining of PBMC revealed that CpG-ODN-induced TNF-alpha derived exclusively from B lymphocytes. TNF-alpha contributed to the CpG-ODN-augmented proliferation and Ig synthesis in PBMC, but was not involved in IFN-gamma synthesis. In conclusion, our findings indicate that certain CpG-ODN induce low amounts of TNF-alpha in human B lymphocytes and may therefore be used to modulate Th2-biased immune responses in allergic patients.

Cytokine/neurotrophin interaction in the aged central nervous system

Age-associated neurodegenerative diseases such as Alzheimer's disease are characterised by neuronal impairment that leads to cognitive deficits. As certain affected neurons depend on trophic factors such as neurotrophins (NTs), impairment in NT function has been suggested to be a component of neuronal damage associated with such disorders. Age-related neurodegenerative diseases are also characterised by high levels of proinflammatory cytokines such as tumour necrosis factor alpha (TNFalpha) in the CNS. Because TNFalpha receptors and certain NT receptors share a high degree of homology and are capable of activating similar signalling pathways, one possibility is that altered cytokine levels may affect NT function in the aged or diseased CNS. Here we wish briefly to review the evidence suggesting a role for cytokine and NT in the onset of age-associated neurodegenerative diseases. We propose that cytokine/NT interactions may alter neuronal homeostasis, thus possibly contributing to some of the neuronal degeneration occurring during such age-associated CNS diseases.

Effects of a pectic polysaccharide from a medicinal herb, the roots of Bupleurum falcatum L. on interleukin 6 production of murine B cells and B cell lines

The effect of T-cell-independent B cell mitogen, a pectic polysaccharide, bupleuran 2IIc, from a medicinal herb, the roots of Bupleurum falcatum L. on interleukin 6 (IL-6) production of murine B cells and B cell lines was investigated in order to clarify the mechanism of enhanced immunoglobulin (Ig) secretion from B cells. Bupleuran 2IIc enhanced IgM secretion from highly purified murine normal B cells. When normal B cells from murine spleen were cultured with bupleuran 2IIc in the presence of anti-IL-6 neutralizing antibody, the enhanced IgM secretion by bupleuran 2IIc was reduced. When B cells were stimulated with bupleuran 2IIc, their IL-6 secretion and the transcription of IL-6 mRNA were enhanced. The enhanced IL-6 secretion by bupleuran 2IIc was also observed in B cell line, Y16 cell. When bupleuran 2IIc was digested with endo-alpha-(1-->4)-D-polygalacturonase, the resulting enzyme resistant carbohydrate portion, "ramified" region (PG-1) composed of rhamnogalacturonan core containing neutral sugar side chains showed potent IL-6 secretion-enhancing activity. These results suggest that the "ramified" region of bupleuran 2IIc stimulates the secretion of IL-6 as the active site, and the resulting IL-6 may partially contribute the enhancement of IgM secretion as an autocrine and/or paracrine mechanism.

Tumor necrosis factor genetic polymorphisms correlate with infections after renal transplantation

BACKGROUND

Nonimmunosuppressed individuals possessing a NcoI restriction enzyme site in the tumor necrosis factor (TNF) gene locus produce less TNF-alpha in vitro and in vivo than do individuals lacking this site. We have previously shown that this NcoI+/low TNF-alpha genotype is independently associated with increased rates of infection for liver transplant recipients.

METHODS

In this study, we performed polymerase chain reaction amplification and restriction fragment length polymorphism analysis of the TNF locus from 45 renal transplant recipients to determine whether the presence of the NcoI site is associated with the frequency of rejection, infection, time to rejection or infection, and patient or graft survival.

RESULTS

Twenty-six recipients were typed with the NcoI+/low TNF-alpha genotype, whereas 19 recipients had the NcoI-/high TNF-alpha genotype. Age, sex, donor type, secondary immunosuppression, use of anti-lymphocyte preparations, graft ischemia time, and year of transplant were evenly distributed in the two groups. There was no difference between the genotype groups in the rate of, or time to, rejection. In contrast, significantly more patients with the NcoI+/low TNF-alpha site developed infections (46% vs. 10% P=0.01). In bivari able models, each controlling for donor type, ischemia time, recipient age, use of antilymphocyte agents, and secondary immunosuppression, the NcoI+/low TNF-alpha genotype was still independently associated with increased numbers of infections (relative risk, 5.38; confidence interval, 1.20-23.8). Conclusion. We conclude that in individuals genetically predetermined to be low TNF-alpha producers, the additional inhibition of TNF-alpha production by routine immunosuppression may be excessive, rendering these individuals less able to respond to infectious stimuli. These patients may benefit from lower doses or withdrawal of corticosteroids, which are known inhibitors of TNF-alpha transcription.

Expression of tumor necrosis factor-alpha in cultured human endothelial cells stimulated with lipopolysaccharide or interleukin-1alpha

Tumor-necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine with a wide variety of biological effects. The most important source of this cytokine is monocytes/macrophages. It is a potent agonist in the activation of endothelial cells; however, the precise role of endothelial cells as a source of TNF-alpha is not known. In the present study, we addressed the possibility that TNF-alpha is produced by cultured human umbilical vein endothelial cells (HUVEC) stimulated with factors such as lipopolysaccharide (LPS) or interleukin-1alpha (IL-1alpha). LPS and IL-1alpha induced expression of TNF-alpha mRNA in HUVEC. IL-1alpha induced expression and secretion of TNF-alpha protein, but LPS did not induce production of TNF-alpha protein. Most of the TNF-alpha protein in cell lysate was found in the membrane fraction. The mRNA for TNF-alpha-converting enzyme (TACE) was expressed in unstimulated HUVEC, and its level was not altered by treatment with LPS or IL-1alpha. Transfection of HUVEC with full-length cDNA encoding the precursor TNF-alpha enhanced secretion of TNF-alpha protein by these cells, and treatment of the cells with a TACE inhibitor reduced the secretion. These results suggest that HUVEC produce TNF-alpha and have TACE activity. Secreted TNF-alpha may be involved in autocrine activation of endothelial cells, and TNF-alpha retained in cell membrane may serve as a juxtacrine system to activate target cells on the endothelial surface.

Role of p52 (NF-kappaB2) in LPS tolerance in a human B cell line

Cells of the weakly CD14 positive human B cell line RPMI 8226, clone 1, will mobilize NF-kappaB (p50/p65 and p50/p50) proteins and produce TNF mRNA when stimulated with lipopolysaccharide (LPS). When such cells are precultured with a low amount of LPS (50-250 ng/ml) for 3 - 4 days followed by a secondary stimulation with a high dose of LPS (1 microg/ml) then the cytokine expression is strongly reduced, i. e. the cells have become tolerant. Western blot analysis of proteins of the NF-kappaB/rel family demonstrates cytoplasmic p50 and p65 for naive B cells plus a low level of p52. While with tolerance induction the pattern of p50 and p65 proteins remains essentially unchanged, the LPS tolerant 8226 cells show a dramatic increase of both p52 protein and its p100 precursor in the cytosol. This p52 is found strongly upregulated in Western blots of extracts from purified nuclei of tolerant cells. Also, gelshift analysis with the -605 kappaB motif of the human TNF 5'-region shows an additional high mobility complex in LPS tolerant cells -a complex that is supershifted with an anti-p52 antibody. Functional analysis with the -1064 TNF 5'-region in front of the luciferase reporter gene demonstrates that transactivation of the TNF promoter is strongly reduced in tolerant cells. Also, overexpression of p52 will suppress activity of TNF promoter reporter gene constructs. Taken together these data show that tolerance to LPS in the human RPMI 8226 B cell line involves upregulation of the p52 (NF-kappaB2) gene, which appears to be instrumental in the blockade of TNF gene expression.

A Defective Protein Kinase C Anchoring System Underlying Age-Associated Impairment in TNF-α Production in Rat Macrophages

The ability of macrophages to secrete cytokines is important in host responses to infections inflammatory stimuli, both of which are altered with aging. In this study, age-associated changes in the release of TNF-α from LPS-stimulated rat alveolar macrophages were determined and correlated with a decrease in the level of RACK1, the anchoring protein involved in protein kinase C translocation and activation. Macrophages from aged rats produced ∼50% less TNF-α than those from young rats. This effect was observed independently from the concentration of LPS used and the time considered. The decrease observed was associated with a defective PKC translocation, due to a reduction in the expression of RACK1, whereas no differences were detected in the expression of LPS receptor (CD14) or total PKC isoforms (α and βΙΙ) in old and young rats. Use of RACK1 antisense oligonucleotide reduced the ability of young macrophages to respond to LPS, further supporting the idea that a deficit in RACK1 contributes to the functional impairment in aged macrophages and that age-induced macrophage immunodeficiencies are associated with alteration in signal transduction pathways.

Kinetics of inflammatory cytokines in the clearance of non-typeable Haemophilus influenzae from the lung

Levels of the pro-inflammatory cytokines TNF-alpha and IFN-gamma were measured from the time of infection to the time of complete clearance of non-typeable Haemophilus influenzae (NTHi) from the lung in immune and non-immune rats. Mucosal immunization facilitated production of significant levels of TNF-alpha as early as 30 min post-pulmonary challenge with NTHi in immune animals. Following the peak at 2 h, rapid decline of TNF-alpha levels occurred from the alveolar spaces. Levels of TNF-alpha in non-immunized animals increased at a slower rate, peaked at a lower concentration and were slower to decline. The significantly larger number of macrophages seen in the immune animals at 1 h after bacterial challenge could partially account for the higher levels of TNF-alpha. Interferon-gamma was not detected in immune or non-immune rats at any time point before NTHi clearance after pulmonary challenge. Study of the kinetics of TNF-alpha release demonstrates that immunized animals control the release of pro-inflammatory cytokines more effectively than non-immunized animals for enhanced clearance of bacterial infection from the lungs.

Cyclosporin A Inhibits Inositol 1,4,5-Trisphosphate Binding to Its Receptors and Release of Calcium from Intracellular Stores in Peritoneal Macrophages

We have studied the effects of the immunosuppressive drug cyclosporin A (CsA) on the generation of inositol 1,4,5-trisphosphate (IP3) and intracellular Ca2+ levels elicited upon ligation of murine macrophage receptors for α2-macroglobulin, bradykinin, epidermal growth factor, and platelet-derived growth factor. Preincubation of cells with CsA (500 ng/ml), either alone or with the various ligands, did not inhibit the synthesis of IP3. However, we observed 70–80% inhibition of the binding of [3H]IP3 to IP3 receptors on macrophage membranes isolated from CsA-treated macrophages. Preincubation of macrophages with CsA abolished IP3-mediated release of Ca2+ from intracellular stores and Ca2+ entry from the extracellular medium observed when macrophage receptors were stimulated with ligands in the absence of CsA. Preincubation of macrophages with CsA also significantly inhibited DNA synthesis induced by ligands for all four receptors studied. Thus in macrophages, as in T cells, CsA blocks receptor-activated signal transmission pathways characterized by an initial increase in intracellular Ca2+ concentration. This inhibition appears to result from a drug effect on IP3 receptors.

The hairy cell leukemia cell line Eskol spontaneously synthesizes tumor necrosis factor-alpha and nitric oxide

Tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) exert a wide array of immunoregulatory, partly related effects. We examined the production of these two mediators by the human hairy cell leukemia cell line Eskol. Combined cell lysate and supernatant of Eskol cells (0.5 x 10(6) cells ml(-1)) incubated for 18 h, contained a mean of 1.5 ng ml(-1) TNF-alpha. This spontaneous TNF-alpha synthesis was enhanced by phorbol ester (PMA) and phytohemagglutinin (PHA) and decreased by dexamethasone. Nitrite, the stable product of NO, accumulated in the supernatant of Eskol cells after prolonged incubation. Maximal nitrite concentrations (range: 0.8-3.5 microM at 2 x 10(6) cells ml(-1)) were detected after 7 days of incubation. NO production was augmented by PHA and reduced by PMA. The inhibitors of NO synthase N(G)-monomethyl-L-arginine (L-NMMA) and aminoguanidine decreased NO synthesis. Simultaneous activation with the proinflammatory cytokines, interferon-gamma, interleukin-1beta and TNF-alpha, increased NO synthesis. These results suggest that NO production in Eskol cells results from inducible NO synthase activity. This is the first direct demonstration of NO formation in human lymphoid cells. The cell line, Eskol, may serve as a model to study regulation of TNF-alpha and NO synthesis in human B-cell leukemia.

Common and idiosyncratic patterns of cytokine gene expression by Epstein-Barr virus transformed human B cell lines

Epstein-Barr virus (EBV) transformed human B cells proliferate indefinitely in vitro, and it has been proposed that cytokine-mediated autocrine loops contribute to the maintenance of the lymphoblastoid phenotype. We used a novel multiprobe RNase protection assay to quantify cytokine mRNA species expressed by EBV-transformed lymphoblastoid cell lines (LCL), derived either by the transformation of B cells with B95-8 or wild-type EBV or by the in vitro outgrowth of EBV-associated B cell lymphomas to identify cytokines that are commonly expressed in all LCL and thus more likely to be essential for immortalization of B cells. All 16 LCL expressed high levels of tumor necrosis factor (TNF)alpha, TNFbeta, and transforming growth factor (TGF)beta1 mRNA, while interleukin (IL)-10 transcripts were detected in most LCL but at a lower level. Expression of IL-1alpha, IL-1beta, IL-6, IL-12p35, IL-12p40, IL-13 and IFNgamma mRNA was variable among the LCL tested. Granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-2, IL-4, and IL-5 mRNA were undetectable in all LCL. Furthermore, we found that IL-10, TNFalpha, and TNFbeta mRNA were induced in EBV-negative B cell lines after infection with EBV. These data define common versus idiosyncratic patterns of cytokine expression by LCL and, in the former case, such cytokines as TNFalpha, TNFbeta, and IL-10 emerge as strong candidates that are essential for the autocrine regulation of EBV-immortalized B cells.

Recombinant Tumor Necrosis Factor Enhances the Locomotion of Memory and Naive B Lymphocytes From Human Tonsils Through the Selective Engagement of the Type II Receptor

Recent studies performed in mice knocked out for the tumor necrosis factor (TNF ), the lymphotoxin-α, or the type I TNF receptor (R), genes have shown that these animals display gross defects in germinal center (GC) formation, suggesting that members of the TNF and TNFR superfamilies are involved in the control of B-cell migration. Based on these premises, we have here investigated the effects of human recombinant (r) TNF on the polarization and locomotion of tonsillar B cells. rTNF increased the spontaneous polarization and locomotion of unfractionated tonsillar B lymphocytes in a dose-dependent manner by inducing a true chemotactic response. Memory (IgD−, CD38−) and naive (IgD+, CD38−), but not GC (IgD−, CD38+) B cells purified from total tonsillar B lymphocytes, showed a significantly higher locomotion in the presence than in the absence of rTNF. Accordingly, type I and II TNF receptors (TNFRs) were detected by flow cytometry on the surface of memory and naive, but not GC, B lymphocytes. Blocking experiments with monoclonal antibodies to type I or II TNFR showed that rTNF enhanced the spontaneous chemotaxis of memory and naive B cells through the selective engagement of type II TNFR. Finally, the TNF gene was found to be expressed in memory, naive and GC B lymphocytes; the cytokine was released in culture supernatants from the three B-cell subsets after stimulation. These data may support the hypothesis that human TNF is involved in the paracrine and perhaps autocrine control of B-cell migration in secondary lymphoid tissues.

Recombinant Tumor Necrosis Factor Enhances the Locomotion of Memory and Naive B Lymphocytes From Human Tonsils Through the Selective Engagement of the Type II Receptor

Recent studies performed in mice knocked out for the tumor necrosis factor (TNF ), the lymphotoxin-α, or the type I TNF receptor (R), genes have shown that these animals display gross defects in germinal center (GC) formation, suggesting that members of the TNF and TNFR superfamilies are involved in the control of B-cell migration. Based on these premises, we have here investigated the effects of human recombinant (r) TNF on the polarization and locomotion of tonsillar B cells. rTNF increased the spontaneous polarization and locomotion of unfractionated tonsillar B lymphocytes in a dose-dependent manner by inducing a true chemotactic response. Memory (IgD−, CD38−) and naive (IgD+, CD38−), but not GC (IgD−, CD38+) B cells purified from total tonsillar B lymphocytes, showed a significantly higher locomotion in the presence than in the absence of rTNF. Accordingly, type I and II TNF receptors (TNFRs) were detected by flow cytometry on the surface of memory and naive, but not GC, B lymphocytes. Blocking experiments with monoclonal antibodies to type I or II TNFR showed that rTNF enhanced the spontaneous chemotaxis of memory and naive B cells through the selective engagement of type II TNFR. Finally, the TNF gene was found to be expressed in memory, naive and GC B lymphocytes; the cytokine was released in culture supernatants from the three B-cell subsets after stimulation. These data may support the hypothesis that human TNF is involved in the paracrine and perhaps autocrine control of B-cell migration in secondary lymphoid tissues.

Effect of hepatitis B virus on tumour necrosis factor (TNF alpha) gene expression in human THP-1 monocytic and Namalwa B-cell lines

In response to viruses, monocytes and B cells produce TNF alpha. Therefore, we investigated TNF alpha gene expression and protein secretion in a human monocytic cell line, THP-1, and a Burkitt's lymphoma B-cell line, Namalwa, in response to hepatitis B virus (HBV). Stimulation by phorbol myristate acetate (PMA) (100 ng/ml for 48 h) induced TNF alpha secretion in THP-1 and Namalwa cells (100 to 300 pg/ml). In THP cells, the optimum response (> 2000 pg/ml) was obtained in the presence of a second mitogenic signal such as lipopolysaccharide (LPS) (10 microg/ml for 24 h). In our activation conditions, Northern blot analysis revealed a marked accumulation of TNF alpha mRNA species at 1.7 kb in both cell lines. When PMA- or PMA+LPS-stimulated THP-1 cells were exposed to HBV, TNF alpha protein and mRNA significantly decreased (> 50%). In contrast, HBV exposure of PMA-activated Namalwa cells resulted in strongly increased TNF alpha protein secretion (1 ng/ml). In this case, HBV induced TNF alpha mRNA accumulation that consisted of two types: a regular 1.7 kb and two novel high molecular weight (HMW) species at 3.7 and 4.3 kb. Exposure of stimulated THP-1 and Namalwa cells to HBV resulted in HBs and pre-S1 antigen production in the supernatants. In addition, HMW HBV DNA forms were detected in both cell lines, but with distinct HindIII restriction patterns. These findings indicate that TNF alpha gene expression may be differently regulated by HBV in activated human macrophages and B cells, and thus TNF alpha may be involved in the pathogenesis of HBV.

Analysis of the first intron of TNFB gene by NcoI RFLP in Koreans

The tumor necrosis factor B (TNFB) gene is closely liked with tumor necrosis factor A (TNFA) gene between the HLA-B and C2 genes on chromosome 6p21.3. Several genetic variabilities at the human TNFB loci have been identified, which are the NcoI restriction fragment length polymorphism (RFLP) in the first intron, amino acid substitution at codon 26 of exon 3 and EcoRI RFLP in untranslated exon 4. The NcoI RFLP of TNFB gene gives two allelic fragments of 238/259 bp and 497 bp, corresponding to TNFB*1 and TNFB*2 alleles, respectively. To investigate the frequency of NcoI RFLP in the first intron of TNFB in Koreans and to compare to that of other ethnic population, genomic DNAs were extracted from leukocytes of 305 unrelated healthy Koreans and amplified the first intron of TNFB gene by PCR. The phenotype frequencies of NcoI RFLP such as TNFB* 1/TNFB*1, TNFB*1/TNFB*2 and TNFB*2/TNFB*2 were 8.6% (n = 26), 45.2% (n = 138) and 46.2% (n = 141), respectively. The estimated allele frequencies for TNFB*1 and TNFB*2 were 0.3115 and 0.6885, respectively. The observed and expected frequencies were in good agreement with the Hardy-Weinberg's equilibrium. The heterozygosity revealed 45.2% and the allele frequencies of NcoI RFLP of TNFB in Koreans were observed comparatively similar to those of other ethnic groups.

The TNF-ligand and receptor superfamilies: controllers of immunity and the Trojan horses of autoimmune disease?

This review is concerned with the tumour necrosis factor receptor and ligand superfamilies, with particular reference to their roles in the immunopathogenesis of Systemic Lupus Erythematosus (SLE). The tumour necrosis factor receptor and ligand superfamilies are well characterized as the molecular controllers of the immune system, acting as 'judges', 'juries', and, where necessary, 'executioners' to determine the fate of immune cells during development, proliferation and differentiation. However, these molecules exert extreme immunopathological effects when unregulated, or dysfunctional. The importance of these molecules in the pathogenesis of autoimmunity is now apparent, and has been considered in detail. Finally, specific consideration has been given to their clinical significance and potential diagnostic and therapeutic applications.

Characterization of a new isoform of the NFAT (nuclear factor of activated T cells) gene family member NFATc

The cyclosporin A (CsA)/FK506-sensitive nuclear factor of activated T cells (NFAT) plays a key role in the inducible expression of cytokine genes in T cells. Although NFAT has been recently shown to be inducible in several non-T immune cells, the NFAT gene family members characterized to date have been isolated only from T cells. To further characterize NFAT function in human B cells and to demonstrate cytokine gene specificity of NFAT proteins, we report here the isolation and characterization of a cDNA clone from the Raji B cell line. The cDNA clone encodes a new isoform, NFATc.beta, of the NFAT gene family member NFATc (designated here NFATc.alpha). The amino acid sequence of NFATc.beta differs from that of NFATc. alpha in the first NH2-terminal 29 residues and contains an additional region of 142 residues at the COOH terminus. Northern analysis using a probe encompassing a common region of both isoforms showed two mRNA species of 2.7 and 4.5 kilobase pairs, while an NFATc.beta-specific probe detected only the 4.5-kilobase pair mRNA which was preferentially expressed in the spleen. Transient expression of NFATc.beta was capable of activating an interleukin-2 NFAT-driven reporter gene in stimulated Jurkat cells in a CsA-sensitive manner. However, NFATc.beta neither bound to the kappa3 element (an NFAT-binding site) in the tumor necrosis factor-alpha promoter nor activated the tumor necrosis factor-alpha promoter in cotransfection assays. These data suggest that different members or isoforms of NFAT gene family may regulate inducible expression of different cytokine genes.

The use of therapeutic drug monitoring to optimise immunosuppressive therapy

Most experience of the therapeutic drug monitoring of immunosuppressive agents has been acquired in the field of solid organ transplantation; however, agents such as cyclosporin (cyclosporin A) are being increasingly utilised for the management of autoimmune diseases. Cyclosporin is the most widely studied immunosuppressant, but in spite of this many controversies still exist as to the optimum strategy for monitoring this drug. Owing to its widely variable pharmacokinetics and metabolism, and the absence of a simple method to measure therapeutic effectiveness, many factors should be considered. In most circumstances, measuring whole blood through concentrations of cyclosporin with a specific assay methodology is warranted. In addition, knowledge of other factors that may alter the pharmacokinetics (such as liver function, concomitant food or medications, gastrointestinal status, and time since transplantation) should be taken into account so that therapy can be appropriately adjusted. Other methods of monitoring have been investigated, such as AUC (area under the concentration-time curve) monitoring and immunological monitoring. However, further refinement of these techniques and greater experience with their efficacy must be accumulated before their role in the monitoring of cyclosporin can be defined. Tacrolimus, like cyclosporin, shares many of the difficulties in monitoring for efficacy and toxicity due largely to the variable pharmacokinetics; similarly to cyclosporin, whole blood through concentration monitoring should be utilised in combination with knowledge of the factors that may affect the pharmacokinetics. Muromonab CD3 (OKT3) is a monoclonal antibody used for the treatment and prophylaxis of acute allograft rejection. Several immunological monitoring techniques have been investigated for this agent. Monitoring CD3+ levels can assist clinicians in determining therapeutic efficacy, while measuring antimuromonab CD3 antibody titres can help determine if xenosensitisation has occurred, causing therapeutic ineffectiveness. The clinical monitoring of azathioprine, one of the first immunosuppressive agents used in transplantation, has historically been limited to monitoring complete blood counts for bone marrow suppression. However, newer techniques measuring intracellular DNA nucleotides appear to be promising. The new immunosuppressants on the horizon include mycophenolate mofetil and rapamycin. The clinical experience with therapeutic drug monitoring of these 2 compounds is scant in the literature; however, both agents have demonstrated efficacy in preventing or treating allograft rejection while maintaining a relatively well tolerated toxicity profile in recent clinical trials. Routine monitoring does not appear to be warranted for immunosuppressive therapy in autoimmune diseases.

O-glycosylated species of natural human tumor-necrosis factor-alpha

Tumor-necrosis factor-alpha, produced by human B-cell lymphoblastoid cell line BALL-1, was expressed as four protein bands on SDS/PAGE analysis. It may have been glycosylated, based on the fact that the heavier two of the four bands disappeared after neuraminidase treatment. Sugar composition analyses revealed that the tumor necrosis factor-alpha contained galactose, N-acetylgalactosamine and N-acetylneuraminic acid as sugar components. To prepare sugar chains, tumor necrosis factor-alpha was treated with alkaline borodeuteride and the oligosaccharide-alditols liberated were fractionated by gel-filtration chromatography on a Bio-Gel P-4 column, followed by normal-phase HPLC. Three oligosaccharide-alditols were obtained, and the structures of two of them were identified by methylation analysis and exoglycosidase digestion. The structures of these oligosaccharide-alditols were Gal beta 1-3(NeuAc alpha 2-6)GalNAcol and Gal beta 1-3GalNAcol (GalNAcol, N-acetylgalactosaminitol). The structure of the remaining oligosaccharide-alditol was determined to be NeuAc alpha 2-3Gal1-3GalNAcol by composition and methylation analyses. About 20% of tumor necrosis factor-alpha was found to be 0-glycosylated, based on the results of the sugar composition and structure analyses. An amino acid sequence analysis of the glycosylated peptides was performed after Staphylococcus aureus V8 protease digestion of tumor necrosis factor-alpha had been completed, and it was proved that the 0-glycosylation site of tumor necrosis factor-alpha was Ser 4.

Relationships between B cell cytokine production in secondary lymphoid follicles and apoptosis of germinal center B lymphocytes

In vivo or in vitro activated human B lymphocytes can produce a wide spectrum of cytokines which are involved in the regulation of hematopoiesis and of the inflammatory and immune responses. Three major B cell subsets have been identified in peripheral lymphoid organs: the germinal center (GC), the mantle zone (MZ) and the marginal zone B lymphocytes. GC and MZ B cells can be isolated as CD39- surface (s)IgD- or CD39+ sIgD+ cells, respectively. Therefore, it is now possible to investigate the cytokine producing potential of purified GC and MZ B lymphocytes. In this article, the optimal conditions for the assessment of cytokine production by human B cells are first discussed; thereafter, the spectrum of B lymphocyte-derived cytokines is described together with their possible physiological meaning. Next, data concerning the cytokines released in vitro by either GC or MZ B cells are presented. Some cytokines, such as granulocyte colony stimulating factor (G-CSF) or granulocyte-macrophage CSF (GM-CSF), are produced only by GC or MZ B lymphocytes, respectively, whereas other cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6) or IL-10 are synthesized by both B cell subsets. Finally, the relationships between B cell-derived cytokines and apoptosis of GC B lymphocytes are discussed, and a hypothetical model of the cytokine networks in secondary lymphoid follicles is presented. It is expected that these notions will help to clarify the pathophysiology of lymphoproliferative and autoimmune diseases.

Effect of lymphocytes on the production of granulomonopoietic enhancing factor by fully mature macrophages

The granulomonopoietic enhancing factor (GM-EF) is a novel myelopoietic regulator produced by human monocyte-derived lipid-containing macrophages (MDLMs). In the present study, we examined the effect of lymphocytes on GM-EF production by preincubation of MDLMs with various preparations of lymphocyte subpopulations in cell-mixed and in double agar layer cultures. Our results showed that a cell concentration-dependent suppression of GM-EF production was noted in cultures with mitogen-activated T cells, and mitogen-activated/resting B cells, while those containing resting T cells had no such effect. Thus, GM-EF production in the presence of 1 x 10(5)/ml activated T cells or activated/resting B cells was greatly reduced to 5% or 20%, respectively. The lymphocyte-induced suppression was evident in both cell-mixed and double layer cultures, implying that the effector cells might exert their influences via mediators. Assay for cytokine activity revealed that a high level (648.2-685.2 pg/ml) of tumor necrosis factor-alpha (TNF-alpha) was found in MDLM cultures with resting/activated B cells, and in those with activated T cells high levels of both TNF-alpha (510.5 pg/ml) and interferon-gamma (IFN-gamma) (321.3 pg/ml) could be detected, whereas in cultures with MDLMs and/or resting T cells, these cytokines were not measurable. Treatment of MDLMs with either recombinant (r) TNF-alpha or rIFN-gamma invariably resulted in a dose-dependent decrease in GM-EF production with intense suppression at doses between 400-800 U/ml.(ABSTRACT TRUNCATED AT 250 WORDS)