High levels of human anti-human antibodies to adalimumab in a patient not responding to adalimumab treatment.
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Adalimumab↗
Biomedical subjects
L Aarden
Publications and source records attributed to L Aarden.
Antibodies to citrullinated human fibrinogen (ACF) have diagnostic and prognostic value in early arthritis.
BACKGROUND: The anti-cyclic citrullinated peptide (CCP) test has a high sensitivity and specificity for rheumatoid arthritis, although CCP is not the physiological target of the autoantibodies. Citrullinated fibrin is abundant in inflamed synovium OBJECTIVE: To assess the diagnostic and prognostic value of antibodies against citrullinated fibrinogen (ACF), a soluble precursor of fibrin, in comparison with IgM-rheumatoid factor (IgM-RF) and the second generation anti-CCP test. METHODS: In 379 patients with early arthritis (258 rheumatoid and 121 undifferentiated), the sensitivity, specificity, and positive predictive value of ACF, anti-CCP, and IgM-RF for diagnosing rheumatoid arthritis were calculated. Multivariate logistic regression analysis was used to assess the diagnostic and prognostic value (radiographic progression after two years) of the tests. RESULTS: The sensitivities of the ACF, anti-CCP, and IgM-RF tests were 55.8%, 57.8%, and 44.6%, with specificities of 92.6%, 94.2%, and 96.7%, respectively. Approximately 30% of the IgM-RF negative patients were positive for ACF or anti-CCP or both. The ACF and anti-CCP test had a high agreement in early arthritis (kappa = 0.84). Of all baseline characteristics, the ACF test and the anti-CCP test were the best predictors for diagnosing rheumatoid arthritis at one year (odds ratio (OR) = 10.3 and 10.6, respectively) and for radiographic progression after two years (OR = 12.1 and 14.8). CONCLUSIONS: ACF is as sensitive as anti-CCP and more sensitive than IgM-RF in diagnosing rheumatoid arthritis in early arthritis. The ACF test is also a good predictor of radiographic progression, with a performance similar to the anti-CCP test. The ACF test and the anti-CCP test are especially valuable in IgM-RF negative arthritis.
Adult↗
From Poisson distribution to interleukins.
Abstract In the mid-1970s, Ivan Lefkovits and co-workers introduced limiting dilution analysis of T and B cells as a method to quantify antigen-specific T and B cells. In this study, I describe how my co-operation with Ivan on the subject led not only to heated discussions on the validity of the approach but also to the identification of interleukin-2 as T-cell-derived factor, capable of replacing T-cell help required for the activation of B cells.
Animals↗
Relationship between serum trough infliximab levels, pretreatment C reactive protein levels, and clinical response to infliximab treatment in patients with rheumatoid arthritis.
OBJECTIVE: To investigate the relationship between serum trough infliximab levels and clinical response to infliximab treatment in patients with rheumatoid arthritis (RA). METHODS: Disease activity and serum trough infliximab levels before and 2, 6, and 14 weeks after initiation of infliximab treatment at a dose of 3 mg/kg in a cohort of 105 patients with RA were assessed. Serum trough infliximab levels in responders and non-responders were compared. Additionally, the clinical responses of patients with high, intermediate, and low serum trough infliximab levels at 14 weeks were compared. RESULTS: After 14 weeks of treatment non-responders had lower serum trough levels of infliximab than responders (median (interquartile range) 0.5 (0.2-2.2) v 3.6 (1.4-8.2) mg/l; p<0.01)). Patients with low serum trough infliximab levels at 14 weeks had significantly less improvement in the 28 joint count Disease Activity Score (DAS28) score than patients with intermediate or high serum trough infliximab levels at 14 weeks. Pretreatment C reactive protein (CRP) levels correlated negatively with serum trough infliximab levels at 14 weeks after the start of treatment (Spearman rank correlation r(s) = -0.43, p<0.001). CONCLUSION: Serum trough levels of infliximab correlate with the clinical response to treatment with infliximab and pretreatment CRP levels. This study indicates that patients with high pretreatment CRP levels might benefit from higher dosages of infliximab or shorter dosing intervals.
Adult↗
Inhibition of interleukin-12 expression by alpha-thrombin in human peripheral blood mononuclear cells: a potential mechanism for modulating Th1/Th2 responses.
In addition to its central role in blood coagulation and hemostasis, human alpha-thrombin is a powerful regulator of inflammatory responses and is known to affect cell-mediated immunity. Interleukin (IL)-12 is a strong promoter of the development of Th1-type lymphocytes and its downregulation implies a positive feedback mechanism for development of Th2 responses. We have previously shown that thrombin enhances the release of IL-6, a Th2-related cytokine, in human peripheral blood mononuclear cells (PBMC). Here we show that thrombin downregulates IL-12 production at both protein and mRNA levels in human PBMC. The inhibition of IL-12 production was accompanied by an enhanced release of IL-10, which inhibits Th1-related processes and promotes Th2-type responses. The use of proteolytically inactive thrombin and of the specific thrombin receptor agonist peptide, SFLLRN, reveals that this downregulation is thrombin-specific and requires thrombin proteolytic activity. In addition, activation of coagulation inhibits IL-12 production in whole blood cultures, confirming the tight relationship between the coagulation pathway, where thrombin is a key enzyme, and inflammation. Decreased IL-12 production appears to be related also to IL-10 production, since the addition of an anti-IL-10 monoclonal antibody to thrombin-treated PBMC resulted in a partial restoration of IL-12 production. In conclusion, the observation that thrombin significantly affects the production of IL-12, as well as of IL-10, implies a concerted role orchestrated by thrombin in PBMC that could be crucial to effective immunity and inflammation.
Gene Expression Regulation↗
Human peripheral blood leukocyte engraftment into SCID mice: critical role of CD4(+) T cells.
We examined the influence of donor T lymphocytes on human peripheral blood leukocytes (PBL) engraftment into severe combined immune deficient (SCID) mice. Mice were injected with unfractionated or subset-depleted human PBL, and treated at various times with OKT3, a cytotoxic monoclonal antibody against human CD3(+) T lymphocytes. PBL engraftment, high levels of human Ig, and high incidence of lymphoproliferative disease (lpd) were found in mice transplanted with unfractionated PBL and CD8- or CD14-depleted PBL, and in mice treated with OKT3 at distance from PBL transfer. Animals xenografted with CD3- or CD4-depleted PBL, or treated at transplantation time with OKT3, had very low levels of human Ig and did not develop lpd. PBL engraftment was minimal or absent in these animals, as determined by immunohistochemistry, dot-blot, and RT-PCR analyses. These results demonstrate that the presence of donor CD4(+) T lymphocytes at transplantation time is necessary for observing human PBL engraftment into SCID mice, an essential condition for human Ig production and lpd development.
Animals↗
Epstein-Barr virus-dependent lymphoproliferative disease: critical role of IL-6.
Epstein-Barr virus (EBV)-induced lymphoproliferative disease (lpd) is a B cell neoplasm that affects patients who are immunosuppressed in the context of organ transplantation or HIV infection. A model for the aggressive form of this entity was generated by xenotransplantation of SCID mice with human peripheral blood leukocytes from individuals with prior contact with EBV. This model, where large B cell lymphoma occurs, was used to test the hypothesis that IL-6 has a major role in EBV-induced B cell tumorigenesis. IL-6 is known to differentiate B cells into immunoglobulin-secreting plasma cells and induce EBV replication, and xenochimeric animals have detectable serum levels of human IL-6. Human IL-6 inhibition with a neutralizing monoclonal antibody decreased tumor incidence from 62 % to 27 %. In addition, anti-IL-6 treatment significantly improved xenotransplanted animal survival, with median survival at > 245 days when compared to that of controls at 132 days. In conclusion, IL-6 plays a critical role in the pathogenesis of EBV-induced human lpd, and IL-6 inhibition may represent a new and promising preventive or therapeutic approach against this malignancy.
Animals↗
Apolipoprotein H, a new mediator in the inflammatory changes ensuring in jeopardised human myocardium.
AIM: To investigate the presence of membrane "flip flop" in ischaemic human myocardium, we assessed depositions of apolipoprotein H (apoH; beta 2-glycoprotein 1) in ischaemic myocardium. Serum protein apoH can bind to negatively charged phospholipids and can also inhibit blood coagulation in vitro. We hypothesised that, because of its affinity for phosphatidyl serine, apoH might bind to "flip flopped" cells and would therefore be useful as a marker for membrane flip flop in vivo. METHODS: Myocardial tissue specimens were obtained from patients who had died within 14 days of acute myocardial infarction. RESULTS: Immunohistochemical analysis of these specimens revealed that apoH was selectively deposited in infarcted areas of human myocardium of at least one day's duration. Depositions of apoH were not found in non-ischaemic myocardial tissue samples obtained from patients who died from other (extracardial) causes. In vitro experiments with the human leukaemia T cell line Jurkat, subjected to apoptosis by etoposide, showed that apoH was bound to the membrane of apoptotic cells. However, these experiments also indicated that flip flop itself is not sufficient for apoH binding. In addition, Jurkat cells that bound apoH were positive for activated complement complexes, as was also found in the human heart. CONCLUSIONS: These results suggest that apoH is involved in the inflammatory processes that occur in ischaemic myocardium.
Apolipoproteins↗
Potential mechanisms for a proinflammatory vascular cytokine response to coagulation activation.
We have previously shown that an anticoagulant could attenuate inflammation in animal models of sepsis with disseminated intravascular coagulation (DIC) and that coagulation activation of human whole blood ex vivo results in a proinflammatory cytokine response. The current studies were performed to better understand mechanisms for the blood cell cytokine response and extend the investigation of such a response to endothelial cells as likely contributors to a vascular inflammatory response. Utilizing cell separation techniques, it was determined that the whole blood IL-8 response to coagulation activation or thrombin, specifically, was mediated by CD14+ monocytes. Moreover, thrombin was observed to stimulate both IL-8 and IL-6 production in cultured mononuclear cells. Analyses of the effects of coagulation activation and thrombin were extended to cultured human endothelial cells, and a similar cytokine response was observed. Thrombin catalytic activity appeared essential, since hirudin reduced thrombin-stimulated proinflammatory cytokine production in cultured monocytes and endothelial cells and prothrombin only weakly mimicked the thrombin response. The endothelial cell IL-8 and IL-6 response to thrombin could be mimicked by the thrombin receptor agonist peptide (TRAP), implicating a functional role of the classic thrombin receptor. Altogether, the results facilitate a better understanding of potential proinflammatory vascular responses to coagulation activation.
Blood Coagulation↗
Soluble Fas levels in sera of bone marrow transplantation recipients are increased during acute graft-versus-host disease but not during infections.
Graft-versus-host disease (GVHD) and infections are two major complications of allogeneic bone marrow transplantation (BMT). In the course of GVHD, one of the pathways that activated cytotoxic T cells use to execute their killing mechanisms is the Fas/Fas ligand pathway. This killing mechanism might be accompanied by the release of soluble Fas (sFas) in the circulation. To examine the association of serum sFas levels and post-BMT complications, we have analyzed sFas levels in sera of bone marrow recipients with and without GVHD. Postallogeneic BMT sFas levels were significantly increased during clinically relevant acute GVHD (aGVHD; P = .002). However, during infections sFas levels tended to decrease (P = .088). Yet, the simultaneous occurrence of GVHD and infections resulted in extreme high sFas levels. These results suggested that sFas release may be correlated with the amount of tissue damage, because aGVHD induces more damage than infections. The presence of significantly increased sFas levels during aGVHD provides new insights into the GVHD pathogenesis.
Adult↗
Sensitive measurement of thrombopoietin by a monoclonal antibody based sandwich enzyme-linked immunosorbent assay.
In this report a sensitive enzyme-linked immunosorbent assay (ELISA) for the measurement of plasma thrombopoietin (Tpo) is described that is solely based on monoclonal antibodies (MoAbs). The assay has an intra and inter-assay variance of 5-7% and 7-13%, respectively. Native and recombinant human Tpo (rhTpo) were recognized equally well, no cross reactivity with other cytokines was found and rhTpo added to plasma and serum was completely recovered. With the ELISA, Tpo concentrations in EDTA-anticoagulated plasma of all controls (n = 193) could be determined, since the limit of detection (2 +/- 0.8 A.U./ml, mean +/- sd) was lower than the concentration found in controls (11 +/- 8 A.U./ml, mean +/- sd; 2.5th-97.5th percentile: 4-32 A.U./ml). Tpo levels in serum were on average 3.4 times higher than in plasma. We showed in vivo that Tpo is bound by platelets, as in thrombocytopenic patients (n = 5) a platelet transfusion immediately led to a drop in plasma Tpo level, whereas in patients receiving chemotherapy the induced thrombocytopenia was followed by a rise in plasma Tpo levels. In summary, these results indicate that this ELISA is a reliable tool for Tpo measurements and is applicable for large scale studies.
Animals↗
The release of interleukin-12 in Escherichia coli-induced lethal and sublethal primate sepsis.
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Animals↗
The proinflammatory cytokine response to coagulation and endotoxin in whole blood.
Acute inflammatory illnesses, including the sepsis syndrome, often include a component of coagulation. A human whole blood culture system was developed so that the relationship between coagulation activation and cytokine responses in the presence or absence of lipopolysaccharide (LPS) could be evaluated. In the absence of LPS stimulation, coagulation activation resulted in a novel pattern of cytokine production. During a 4-hour culture of coagulating blood, significant production of interleukin-8 (IL-8; >2,000 pg/mL) was observed, whereas other proinflammatory cytokines including IL-1 beta, IL-6, or tumor necrosis factor a were undetectable or less than 35 pg/mL. The cytokine profile was distinct from that of fully anticoagulated, LPS-stimulated blood, which showed levels of all the indicated proinflammatory cytokines > or = 2,000 pg/mL over the same time period. Over 24 to 48 hours, the coagulation-induced cytokine response was characterized by marked and sustained IL-8 production, limited IL-6 generation (with kinetics delayed relative to IL-8), and minimal or undetectable tumor necrosis factor alpha levels. The magnitude of the whole blood IL-8 response correlated with the level of coagulation activation as determined by measurement of thrombin-antithrombin III complex formation. The combined stimuli of coagulation activation and LPS challenge induced a synergistic enhancement of IL-8 production but not of IL-6. Coagulation-induced cytokine production and the synergistic production of IL-8 by coagulation and LPS could be attenuated by hirudin or tissue factor pathway inhibitor (TFPI). Studies to elucidate mechanisms implicated (1) the TFPI third Kunitz and carboxy-terminus as important structural components for TFPI regulation of coagulation activation and (2) thrombin as a candidate mediator of the mononuclear cell cytokine response to coagulation activation. In summary, a unique aspect of the crosstalk between the coagulation and cytokine cascades in whole blood is shown with the identification of IL-8 as a key proinflammatory participant.
Blood Coagulation↗
On the interaction between agalactosyl IgG and Fc gamma receptors.
One of the serum abnormalities observed in autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) is the occurrence of IgG that lacks the terminal galactose on asparagine-linked biantennary complex type oligosaccharides [Gal(0)-IgG] located in the CH2 domain. Additionally, IgG without glycosylation is known to be defective in several effector functions due to a reduced ability to bind to its specific receptors (Fc gamma R). It has thus been speculated that, by analogy with unglycosylated IgG, Gal(0)-IgG may also be functionally impaired or exert altered effector mechanisms. If this were true, Gal(0)-IgG could contribute to the phenotype of above-mentioned autoimmune diseases, like impaired immune complex clearance and defective down-regulation of activated B cells. Here, we show by three different methods that the interaction of Gal(0)-IgG and normally glycosylated IgG with the low-affinity Fc gamma RII (CD32) is indistinguishable with respect both to binding and receptor-mediated signalling. These data argue against a prominent role for Fc gamma R-dependent Gal(0)-IgG interactions in the etiology or pathogenesis of autoimmune diseases.
Animals↗
Functional analysis of synovial fluid and peripheral blood T cells from patients with rheumatoid arthritis.
Rheumatoid arthritis is a T cell-mediated autoimmune disease. The lack of knowledge of the involved target antigens severely hampers research on relevant T cells in patients. Here we describe the functional analysis of freshly isolated T cells from the peripheral blood and the site of the lesion (synovial fluid or synovial membrane) of patients with rheumatoid arthritis. Healthy donors and osteoarthritis patients served as controls. Using various polyclonal stimuli, we analyzed CD4+ T cells with respect to proliferation and their ability to produce lymphokines. Our data show that lesion-derived CD4+ T cells of patients with rheumatoid arthritis are severely defective in proliferation and lymphokine (interleukin-2, interleukin-4, tumor necrosis factor-alpha, interferon-gamma) production. This activation defect was most pronounced at lower cell densities and was present in both synovial fluid derived and synovial membrane derived CD4+ T cells of all patients tested. No difference was found between responses of synovial fluid derived CD4+ T cells from osteoarthritis patients and those observed with peripheral blood derived T cells from all groups. The observed defect in lesion-derived CD4+ T cells from rheumatoid arthritis patients was not due to the effect of inflammatory factors in the synovial fluid because preincubation with synovial fluid could not induce a similar defect in control T cells. Together, our data show a rheumatoid arthritis specific, general defect in the activation of lesion-derived CD4+ T cells.
Adult↗
TNF-alpha induces spreading of B-CLL via the CD11c/CD18 molecule.
Activation of malignant B cells can lead to extensive morphological changes of these cells. A combination of PMA and TNF-alpha can induce adherence of purified B-CLL cells, which acquire a dendritic cell-like appearance. This phenomenon that we have termed spreading, is accompanied by upregulation of expression of both beta 1 and beta 2 integrin molecules. Spreading was inhibited by the addition of antibodies against CD18 or CD11c. In other B cell malignancies (HCL and NHL), morphological changes could be induced by PMA in the absence of TNF-alpha. Culturing in the presence of prednisolone resulted in an inhibition of spreading, most likely mediated via a down regulation of CD18 and CD11c expression. These data indicate that the CD11c/CD18 complex might be important for the adhesive properties of B cells.
Antigens, CD↗
Development of human Th1 and Th2 cytokine responses: the cytokine production profile of T cells is dictated by the primary in vitro stimulus.
Regulation of interleukin (IL)-4 production, but not IL-2 production, was found to be quite different in either freshly isolated T cells or T cell clones. Both fresh T cells and T helper 2-like clones produced IL-4 when stimulated with anti-CD2 in combination with anti-CD28. However, whereas T cell clones showed enhanced IL-4 production when phorbol 12-myristate 13-acetate (PMA) was used in addition to anti-CD2 and anti-CD28, IL-4 production by fresh T cells was inhibited by the presence of PMA. Prestimulation of fresh T cells led to the following observations: (a) activation in the absence of PMA led to a reversal of the PMA effect and (b) within 2 days these cells resembled T cell clones in that IL-4 production was no longer inhibited by PMA. When prestimulation was carried out in the presence of PMA, the inhibition of IL-4 production seemed irreversible. Removal of PMA after 3 days did not lead to renewed capability of IL-4 production, whereas IL-2 production was unimpaired. Our data show that the capacity of cultured T cells to produce IL-4 is determined and fixed during the first 2-3 days of stimulation.
Antigens, CD↗
Modulation of IL-6 production and IL-1 activity by keratinocyte-fibroblast interaction.
The present study was undertaken to investigate whether modulation of interleukin-6 and interleukin-1 production occurs owing to keratinocyte-fibroblast interaction. Normal human keratinocytes or squamous carcinoma cells were cultured either alone or in the presence of human foreskin fibroblasts or murine 3T3 cells. All cells tested produced interleukin-6, and interleukin-6 levels were markedly increased when normal or malignant keratinocytes were co-cultured with fibroblasts. The bioassay (species independent) and enzyme-linked immunosorbent assay (specific for human interleukin-6) together with use of complementary DNA probes specific for human or murine interleukin-6 revealed that fibroblasts are responsible for increased interleukin-6 levels. Moreover, interleukin-6 levels were increased when fibroblasts were cultured in conditioned media derived from normal human keratinocytes and squamous carcinoma cells-4 cultures. Interleukin-1 alpha secreted by normal human keratinocytes and squamous carcinoma cells-4 cells was mainly responsible for the increased interleukin-6 production in fibroblasts. Although interleukin-1 activity increased linearly with the incubation time in squamous carcinoma cells-4 monocultures, interleukin-1 activity was low and remained unchanged in squamous carcinoma cells-4/3T3 co-cultures. Low interleukin-1 activity was most probably not due to inhibition of interleukin-1 alpha production in squamous carcinoma cells-4/3T3 co-cultures because interleukin-1 alpha messenger RNA expression in squamous carcinoma cells-4 cells remained unchanged in the presence of 3T3 cells. Furthermore, when 3T3 cells were incubated in conditioned medium derived from squamous carcinoma cells-4 cells, high interleukin-1 activity decreased to an undetectable level, suggesting that fibroblasts are involved in the suppression of interleukin-1 activity. The remaining interleukin-1 activity, however, was sufficient for maximal induction of interleukin-6 production in fibroblasts. These results suggest that the interaction between epithelial and mesenchymal cells is at least partly initiated by interleukin-1 alpha secreted by the activated epithelial cell during skin injury or tumor invasion. Interleukin-1 in turn can induce modulation of the synthesis of various pro-inflammatory mediators and proteases in surrounding fibroblasts. An enhanced proteolytic activity and/or a possible induced production of an interleukin-1 inhibitor in fibroblasts and/or a receptor-mediated interleukin-1 consumption by fibroblasts will cause a decrease in interleukin-1 activity and thus exert a negative feedback.
3T3 Cells↗