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Biomedical subjects

W J Koopman

Publications and source records attributed to W J Koopman.

At least 37 records · Page 2Linked to original sources
PubMed1998

Dendritic cells from Peyer's patch and spleen induce different T helper cell responses.

The role of antigen-presenting cells (APC) in regulating the balance of T helper type 1 (Th1) and T helper type 2 (Th2) responses and cytokine production is unclear. Dendritic cells (DC), the most potent APC for naive T cell activation, were found to regulate Th1 and Th2 cytokine profiles in a manner dependent on their tissue of origin. Using whole tissues or purified cell mixtures, spleen (systemic) DC were found to induce mainly Th1 cytokines, and Peyer's patch (mucosal) DC were found to induce predominantly Th2 cytokines. Spleen DC induced high levels of interferon-gamma (IFN-gamma) or interleukin-2 (IL-2) or both, and Peyer's patch DC induced IL-4 or IL-6 or both in spleen and Peyer's patch T cells, allogeneic mixed leukocyte reactions, or antigen-specific Th0 clones. These data suggest that the tissue of origin of DC has a significant impact on subsequent T cell development.

Animals↗
PubMed1998

Nondepleting humanized anti-CD4 monoclonal antibody in patients with refractory rheumatoid arthritis.

OBJECTIVE: To investigate the safety, tolerability, pharmacokinetics, and immunologic activity of single intravenous infusions (0.2-10 mg/kg) of Orthoclone OKTcdr4a, a nondepleting humanized anti-CD4 monoclonal antibody (Mab) in patients with rheumatoid arthritis. METHODS: Eighteen patients were treated with a single intravenous dose of Mab. Three patients each received 0.2, 0.5, 1.0, 2.0, 5.0, or 10.0 mg/kg of OKTcdr4a. RESULTS: No patient had a significant change in CD4+ T cells in peripheral blood after treatment. No human antimurine antibodies were detected. At > or = 1.0 mg/kg dose level, CD4 receptor saturation was > or = 95% 24 h after infusion. At 5.0 mg/kg, CD4 receptor occupancy was a mean of 88% at 6 days after infusion. At 10 mg/kg, CD4 receptor occupancy was still a mean of 79% 2 weeks after infusion. No significant infusion related adverse events occurred. Two subjects had headaches at the time of drug administration. Two subjects were hospitalized for infections (pneumonia, Day 45; cellulitis, Day 14), which resolved with antibiotic therapy. CONCLUSION: OKTcdr4a was well tolerated at the doses used and saturation of CD4 receptors in peripheral blood could be routinely obtained for over one week with a single infusion of Mab.

Adult↗
PubMed1998

Clonally-related immunoglobulin VH domains and nonrandom use of DH gene segments in rheumatoid arthritis synovium.

BACKGROUND: Synovia of patients with long-standing rheumatoid arthritis (RA) are typically infiltrated with B lymphocytes and plasma cells that secrete large amounts of immunoglobulin. The CDR3 of an immunoglobulin heavy chain is composed of the VH-DH-JH join, with interposed N region addition, and thus defines clonal relatedness. Furthermore, the CDR3 lies at the center of the antigen binding site, so its length and composition influence antigen binding. We sought definitive evidence of an antigen-driven B cell response (i.e., clones derived from the same VH, DH, and JH gene segments with shared somatic mutations) in RA synovial mRNA transcripts, and to characterize CDR3 intervals at the target of inflammation in this autoimmune disease. MATERIALS AND METHODS: We screened a cDNA library generated from unselected cells from the knee joint of a 62-year-old white female with long-standing RA. This technique does not have the potential bias of selecting for antibodies that express a particular reactivity such as rheumatoid factor. C gamma recombinants were sequenced and progenitor VH, DH, and JH gene segments were assigned and somatic mutations determined by comparison to germline sequences. Analyses of DH reading frame utilization and hydropathy characteristics of CDR3s were performed. RESULTS: Two of 67 recombinants were derived from the same VH (V3-11) and JH gene segments, demonstrated shared mutations, and contained nearly identical VH-DH-JH joins, including N region addition. Three other recombinants contained identical sequence throughout the variable domain. We also found preferential utilization of a limited number of VH and DH gene segments and marked preference for a DH reading frame encoding predominantly hydrophilic residues. CONCLUSIONS: Analysis of expressed heavy chain variable domains strongly supports the hypothesis that the B cell response in RA synovium is at least in part antigen driven and oligoclonal.

Amino Acid Sequence↗
PubMed1998

Enhanced expression of immunoglobulin kappa light chains with unusually long CDR3 regions in patients with rheumatoid arthritis.

OBJECTIVE: Our previous sequence analysis of immunoglobulin kappa light chains revealed that some patients with rheumatoid arthritis (RA) expressed repertoires enriched for transcripts containing unusually long CDR3 lengths of 11 amino acid codons. This was due, in part, to N region addition at the Vkappa-Jkappa joins. In this study, we analyzed a larger number of individuals to determine how often enrichment of kappa light chain repertoires for 11 amino acid CDR3 occurs in synovial lymphocytes and peripheral blood lymphocytes (PBL) of individuals with RA. METHODS: To measure length variability of kappa chain CDR3 regions, we performed a 2 stage polymerase chain reaction amplification and polyacrylamide gel electrophoresis. We sampled PBL and synovial lymphocytes of 9 patients with longstanding RA, and used PBL of 9 age and sex matched healthy individuals as controls. RESULTS: In PBL of healthy individuals, there was low level but consistent expression of kappa chains containing CDR3 with 11 amino acids. In patients, there was enhanced expression of kappa chains containing CDR3 with 11 amino acids compared to healthy individuals. This enhanced expression of kappa chains containing CDR3 of 11 amino acids was more pronounced in synovial lymphocytes compared to PBL of the same patients. CONCLUSION: These findings suggest that there is antigenic selection of B cells bearing antibodies with unusually long kappa light chain CDR3 in RA.

Adult↗
PubMed1997

Treatment of rheumatoid arthritis with a recombinant human tumor necrosis factor receptor (p75)-Fc fusion protein.

BACKGROUND: Tumor necrosis factor (TNF) is a proinflammatory cytokine involved in the pathogenesis of rheumatoid arthritis, and antagonism of TNF may reduce the activity of the disease. This study evaluated the safety and efficacy of a novel TNF antagonist - a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1 (TNFR:Fc). METHODS: In this multicenter, double-blind trial, we randomly assigned 180 patients with refractory rheumatoid arthritis to receive subcutaneous injections of placebo or one of three doses of TNFR:Fc (0.25, 2, or 16 mg per square meter of body-surface area) twice weekly for three months. The clinical response was measured by changes in composite symptoms of arthritis defined according to American College of Rheumatology criteria. RESULTS: Treatment with TNFR:Fc led to significant reductions in disease activity, and the therapeutic effects of TNFR:Fc were dose-related. At three months, 75 percent of the patients in the group assigned to 16 mg of TNFR:Fc per square meter had improvement of 20 percent or more in symptoms, as compared with 14 percent in the placebo group (P<0.001). In the group assigned to 16 mg per square meter, the mean percent reduction in the number of tender or swollen joints at three months was 61 percent, as compared with 25 percent in the placebo group (P<0.001). The most common adverse events were mild injection-site reactions and mild upper respiratory tract symptoms. There were no dose-limiting toxic effects, and no antibodies to TNFR:Fc were detected in serum samples. CONCLUSIONS: In this three-month trial TNFR:Fc was safe, well tolerated, and associated with improvement in the inflammatory symptoms of rheumatoid arthritis.

Antibodies↗
PubMed1997

Kinetics of calcium steps underlying calcium oscillations in melanotrope cells of Xenopus laevis.

Melanotrope cells of Xenopus laevis display intracellular calcium oscillations which are generated at the plasma membrane and travel as a wave through the cytoplasm into the nucleus. An oscillation involves discrete increases in intracellular Ca2+ ('steps'), followed by a relatively smooth return to the basal Ca2+ level. The aim of our investigation was to determine what role these steps play in shaping the Ca2+ signal in melanotrope cells, by conducting a high resolution spatio-temporal analysis of the kinetics of the Ca2+ steps. To this end Fura-red loaded cells were analysed by confocal laser scanning microscopy using the line scanning method to achieve 6 ms time resolution. Furthermore, the kinetics of the steps were analysed in 3 different intracellular areas, to see if there are spatial differences in Ca2+ signalling kinetics. The results showed that each calcium oscillation is built up by 3-4 steps that were generated very quickly and had approximately the same size. Following each Ca2+ step, there was a slow removal of calcium before the next step boosted the overall level of Ca2+. Since the Ca2+ steps were most pronounced directly beneath the plasma membrane, they appear to be generated in this region. The speed of the Ca2+ wave near the membrane exceeded 40 microns/s, indicating an active mechanism for wave propagation. In deeper regions of the cell, the wave speed was much slower (about 8 microns/s) and the size of each step was smaller, indicating that regulation occurs within a narrower range of [Ca2+]i. Inside the nucleus, however, the calcium wave accelerated again (23 microns/s). Treatment with TRH evoked a high amplitude Ca2+ transient and increased the number of Ca2+ steps to 5 or 6. Each step had approximately the same size as the steps of the pretreatment Ca2+ oscillations. Caffeine treatment, which increased the frequency of the oscillations, had no effect on the number or the size of the Ca2+ steps, but it reduced the time needed for each step to reach its maximum height. We suggest a possible 'building block' function for the Ca2+ steps, whereby a cell generates more steps to achieve a high oscillation amplitude or accelerates the speed of the steps to increase the frequency of oscillations. Both phenomena may play a crucial role in the encoding of information transduced from an extracellular input to the intracellular target.

Animals↗
PubMed1996

Dendritic cells from different tissues induce production of different T cell cytokine profiles.

The precise role of antigen-presenting cells (APC) in regulating the balance of T-helper type 1 (Th1) and T-helper type 2 (Th2) cytokine production is unclear. Dendritic cells (DC), the most potent APC for activation of naive T cells, were found to regulate Th1 and Th2 cytokine profiles in a fashion dependent upon their tissue of origin. Spleen (systemic) DC induce mainly Th1 cytokines and Peyer's patch (mucosal) DC induce predominantly Th2 cytokines. These findings support the current concept that different tissues, each with its distinct microenvironment of cytokines, hormones, and cellular elements, are involved in the selection, promotion, and/or maintenance of different immune responses. With regard to DC, it is apparent that the tissue of DC origin determines the cytokine profiles produced by T cells and that DC from different tissues favor either cellular versus humoral immune responses by influencing T cell cytokine production.

Animals↗
PubMed1996

V beta 17 T cell receptor peptide vaccination in rheumatoid arthritis: results of phase I dose escalation study.

OBJECTIVE: To determine whether modulation of activated T cells occurs in patients with rheumatoid arthritis (RA) after immunization with T cell receptor (TCR) V beta 17 peptides, a phase I trial was initiated to investigate the safety and feasibility of TCR peptide immunization as a therapeutic approach in RA. METHODS: 15 patients with moderate to severe RA were given an intramuscular injection of one of 4 doses (10, 30, 100, and 300 micrograms) of the V beta 17 peptide vaccination, followed by a booster injection of the same dose of vaccine 3 weeks later. Patients were followed for 48 weeks. RESULTS: The product was well tolerated and no serious adverse events attributable to the vaccine were observed. This was an uncontrolled phase I trial, however; decreases in patients joint scores were observed at all followup visits starting at 4 weeks after primary immunization. Activated V beta 17 T cells (IL-2R+) in peripheral blood were decreased (> or = 20%) in 3/5 patients in the 100 micrograms group after initial measurement at Week 2 and 3/4 patients in the 300 micrograms group 3 weeks after immunization. Lymphocyte proliferation in response to the V beta 17 peptide was detected at 6 weeks or later after primary inoculation in 6/15 patients (40%) immunized. CONCLUSION: Further controlled studies are required to assess the biologic and clinical efficacy of this treatment approach.

Adult↗
PubMed1996

Suppression of in vitro IgM rheumatoid factor production by diphtheria toxin interleukin 2 recombinant fusion protein (DAB 486IL-2) in patients with refractory rheumatoid arthritis.

OBJECTIVE: To investigate the effect of diphtheria toxin interleukin 2 recombinant fusion protein (DAB 486IL-2) on in vitro synthesis of immunoglobulin and rheumatoid factor (RF) in patients with severe refractory rheumatoid arthritis (RA) enrolled in a phase II, double blind, placebo controlled study. METHODS: Anticoagulated venous blood samples were obtained before (Day 1) and after (Day 28) intravenous infusion of either DAB 486IL-2 at 0.075 mg/kg/day (12 patients) or saline placebo (10 patients) on Days 1-5. Peripheral blood leukocytes (PBL) were prepared by density gradient centrifugation, cultured in the presence and absence of pokeweed mitogen (PWM) for one week, and culture supernatants assayed for immunoglobulins and IgM RF by ELISA. RESULTS: Compared to placebo treated patients, PWM induced IgM RF synthesis by PBL decreased after treatment with DAB 486IL-2 (p = 0.043). However, there was no apparent correlation with clinical improvement. PWM induced IgM, IgA, and IgG synthesis also tended to decrease, although the changes did not attain statistical significance. In contrast, PWM induced IgM RF, IgM, IgA, and IgG synthesis by PBL from patients treated with placebo tended to increase during the observation period. Spontaneous immunoglobulin and IgM RF production by PBL from either the DAB 486IL-2 or placebo patients remained stable. CONCLUSION: These observations raise the possibility that DAB 486IL-2 may diminish B cell function either directly or indirectly through effects on T cell function, but the change may not correspond to clinical response.

Adolescent↗
PubMed1996

Recombinant soluble tumor necrosis factor receptor (p80) fusion protein: toxicity and dose finding trial in refractory rheumatoid arthritis.

OBJECTIVE: To determine the safety and pharmacokinetics of recombinant human tumor necrosis factor receptor (p80) fusion protein (rhTNFR:Fc) administered as a single intravenous (iv) loading dose followed by subcutaneous (sc) maintenance injections twice weekly for one month in patients with refractory rheumatoid arthritis (RA). METHODS: Four dose groups were evaluated with 4 patients with RA per group: 3 received active drug and one received placebo injection. After each dose group completed 4 weeks of treatment, the patient who received placebo was allowed to receive the active drug for one month. After these 16 patients completed the study, 3 additional patients received the highest dose and 3 additional patients received the lowest dose in an open label study to obtain more safety data (total of 22 patients treated). RESULTS: There were no serious adverse effects. Drug related events include mild injection site reactions in 4 patients that did not necessitate discontinuation of the drug. There was no clearcut dose response among the treatment groups. At Week 4, there was 45% mean improvement in total pain and total joint scores in patients receiving active drug (n = 12), compared to 22% mean improvement in patients receiving placebo (n = 4). C-reactive protein (CRP) levels decreased substantially in patients treated with drug compared to placebo, 30 vs 13%, respectively. The decrease in CRP was most pronounced in the highest dose group. CONCLUSION: This initial experience with rhTNFR:Fc fusion protein in RA justifies further evaluation of this agent in a larger placebo controlled trial.

Adult↗
PubMed1995

Characterization of human Fas gene. Exon/intron organization and promoter region.

Ligation of the Fas cell-surface molecule induces apoptosis. Defective Fas-mediated apoptosis has been associated with spontaneous autoimmunity in mice. Using human Fas/Apo-1 cDNA as a probe, we have molecularly cloned and characterized the human Fas chromosomal gene. The gene consists of nine exons and spans more than 26 kilobases of DNA. The lengths of introns vary from > 14 kilobases at the 5' end of the gene to 152 base pairs upstream of the exon encoding the transmembrane domain. The domain structure of the human Fas is encoded by an exon or a set of exons. Primer extension analysis revealed three major transcription initiation sites. The promoter region lacked canonical "TATA" and "CAAT" boxes but was a "GC-rich" sequence, and contained consensus sequences for AP-1, GF-1, NY-Y, CP-2, EBP20, and c-myb. These data provide the first characterization of the human Fas gene and insight into its regulatory region.

Amino Acid Sequence↗
PubMed1995

Progressive joint destruction in a human immunodeficiency virus-infected patient with rheumatoid arthritis.

This article reports the case of a 63-year-old patient with rheumatoid arthritis (RA) whose symptoms of RA improved after the occurrence of a secondary human immunodeficiency virus (HIV) infection; however, the HIV infection did not affect the histologic parameters of joint destruction to the same extent as it did the clinical symptoms. Histologic and immunohistologic joint examinations of this patient revealed an ongoing production of cartilage- and bone-degrading enzymes by macrophages and fibroblasts, without the presence of T cells. These findings demonstrate that progressive joint destruction in RA can occur in the absence of T cells. Moreover, our results support the hypothesis that both T cell-dependent and T cell-independent pathways play a significant role in the pathogenesis of RA.

Arthritis, Rheumatoid↗