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C Schönemann

Publications and source records attributed to C Schönemann.

14 recordsLinked to original sources
PubMed2006

Heightened expression of the cytotoxicity receptor NKG2D correlates with acute and chronic nephropathy after kidney transplantation.

The activating cytotoxicity receptor NKG2D binds to stress-regulated molecules encoded by the major histocompatibility complex class I chain-related (MIC) and UL-16-binding protein (ULBP)/retinoic acid early transcript (RAET) gene family. To assess whether acute allograft rejection leads to an induction of these inducible ligands and their receptor NKG2D, we examined the mRNA profiles in kidney transplant biopsies. Expression levels were correlated with the incidence of acute rejection (aRx) episodes and chronic allograft nephropathy (CAN) proven by histology. Whereas MICA, ULBP1/3 and RAET1-E did not display heightened gene expression, elevated levels of NKG2D mRNA could be associated with aRx (p < 0.001). Immunohistology of kidney biopsies diagnosed with aRx revealed NKG2D+ cells in tubulointerstitial areas positive for CD8+ cells. Most importantly, elevated levels of NKG2D mRNA were associated with restricted long-term graft function assessed by the glomerular filtration rate at 6, 12 and 18 months posttransplantation. Induced NKG2D mRNA expression was still observable in biopsies diagnosed with CAN (p < 0.001), demonstrating a higher sensitivity and specificity compared to CD3, granzyme B and granulysin mRNA measurement. Significant elevated levels of NKG2D mRNA could be further detected in urine sediment prior to aRx, suggesting this receptor as a new candidate marker for the diagnosis of acute and chronic allograft rejection.

Acute Disease↗
PubMed2006

A simple and practical agglutination assay for human leucocyte antigen-B27 typing.

BACKGROUND AND OBJECTIVES: The human leucocyte antigen (HLA) B27 is the most frequently typed single antigen that is associated with diseases. Here, we describe a simple and rapid particle agglutination assay (PaGIA) for HLA-B27 typing. MATERIALS AND METHODS: Superparamagnetic particles were coated with a monoclonal antibody to HLA-B27 and subsequently used for testing. Anticoagulated whole-blood samples were obtained from healthy blood donors (n = 194) with known HLA patterns and from patients (n = 51) who had been typed positive for HLA-B27 by flow cytometry. RESULTS: The particles agglutinated only after incubation with HLA-27-positive blood samples, using the ID-microtyping system. Positive reactions were clearly distinguishable from negative reactions in all samples tested. Flow cytometric HLA-B27 typing revealed an indeterminate result in one patient. CONCLUSIONS: The new HLA-B27 PaGIA is suitable for rapid typing of HLA-B27. The assay is simple and easy to perform, and can be implemented in any routine laboratory.

Agglutination Tests↗
PubMed2006

ELISA methods detect HLA antibodies with variable sensitivity.

The accuracy of human leukocyte antigen (HLA) antibody screening results is dependent on the technique employed. In this study, a total of 612 serum samples from patients awaiting kidney transplantation were tested by two different enzyme-linked immunosorbent assay (ELISA) methods: LAT-M(R) (One Lambda/BMT) and AbScreen(R) (Biotest). The results of these assays were identical for HLA class I and II antibodies in 524 cases (85.6%), and discrepant in the remaining 88 cases (42 class I, 24 class II, 22 class I and II). More specifically, class I results were in agreement in 26 positive and 522 negative cases and in disagreement in 64 cases. Class II results were the same in 50 positive and 516 negative cases and different in 46 cases. Retesting the samples using LAT 1288 (One Lambda/BMT) and considering previous HLA antibody test results and the history of immunising events, the sensitivity and specificity, respectively, of the two methods were determined as follows: class I: 89.6% and 97.5% (LAT-M) vs. 70.6% and 96.8% (AbScreen), class II: 96.5% and 98.4% (LAT-M) vs. 88.3% and 95.5% (AbScreen). These results indicate that a single ELISA does not invariably prove or exclude the presence of HLA antibodies, and that additional testing is required in some cases.

Antibody Specificity↗
PubMed2000

Analysis of CD8 T cell reactivity to cytomegalovirus using protein-spanning pools of overlapping pentadecapeptides.

The frequencies of human cytomegalovirus (HCMV) protein-specific CD8 T cells, identified by the presence of intracellular IFN-gamma, were measured by flow cytometry following stimulation of freshly isolated peripheral blood mononuclear cells (PBMC) with comprehensive peptide pools. These pools spanned the entire amino acid sequences of the HCMV pp65 and major immediate early (IE-1) proteins and consisted of 15-amino acid peptides with at least nine overlaps between neighboring peptides. As a result all potential CD8 T cell epitopes contained in these proteins were provided by the complete pools and, therefore, unlike with single epitopes, testing was independent of donor HLA type. Individual stimulating peptides from the same pools were identified in parallel experiments. Thus we found that our results with the complete pools using PBMC from 26 healthy HCMV-seropositive donors were 100% sensitive and specific with respect to predicting the presence of recognized epitopes in the respective proteins. In addition, cells from 15 renal transplant patients were tested with complete pools alone. While our results confirmed our previous contention that HCMV IE-1 is an important CD8 T cell target, the technical improvement we made in order to address this question has clearly wider implications. Similar pools may be applied to examine the role of proteins from other pathogens, in autoimmune disease or following vaccination.

Amino Acid Sequence↗
PubMed1999

Target structures of the CD8(+)-T-cell response to human cytomegalovirus: the 72-kilodalton major immediate-early protein revisited.

Cell-mediated immunity plays an essential role in the control of infection with the human cytomegalovirus (HCMV). However, only a few CD8(+)-T-cell epitopes are known, with the majority being contained in the pp65 phosphoprotein, which is believed to dominate the CD8(+)-T-cell response to HCMV. Here, we have readdressed the issue of CD8(+) T cells specific for the 72-kDa major immediate-early protein (IE-1), which is nonstructural but is found very early and throughout the replicative cycle. Using a novel flow-cytometric assay, we were able to identify CD8(+)-T-cell epitopes (by IE-1 peptide-specific induction of cytokine synthesis) and simultaneously measure the frequency of cells directed against them. For this purpose, 81 pentadecamer peptides covering the complete 491-amino-acid sequence of IE-1 were tested on peripheral blood mononuclear cells of anti-HCMV immunoglobulin G-seropositive donors. At least 10 new epitopes were identified, and the fine specificity and presenting HLA molecule of the first of them was determined. The frequencies of CD8(+) T cells directed against IE-1 were similar to those directed against pp65 in donors tested with known pp65-derived peptides. Importantly, additional testing of a corresponding set of peptides covering the complete sequence of pp65 on 10 of these donors identified individuals whose CD8(+) T cells recognized IE-1 but not pp65 and vice versa, clearly illustrating that either protein may be a major target. In summary, our results suggest that IE-1 is far more important as a CD8(+)-T-cell target than current opinion suggests.

Antigen Presentation↗
PubMed1998

HLA class I and class II antibodies: monitoring before and after kidney transplantation and their clinical relevance.

BACKGROUND: In search of an alternative screening technique, we compared complement-dependent cytotoxicity (CDC) with PRA-STAT, a commercially available enzyme-linked immunosorbent assay (ELISA). METHODS: A total of 188 pre- and posttransplant sera from 50 renal allograft recipients were tested with both methods. RESULTS: A significant correlation was found between both methods. Discrepant results could be explained by the fact that PRA-STAT detects both HLA class I and II antibodies (while CDC with peripheral blood lymphocytes as target cell detects mainly HLA class I reactivity), by the presence of IgM antibodies (which are not detected by the IgG-specific ELISA test), and by CDC "false-positive" results due to antibody rejection treatment. The clinical relevance of antibodies detected by PRA-STAT is suggested by the following. (a) In eight patients, donor-specific HLA antibodies detected by PRA-STAT (but not seen by CDC) resulted in severe rejection episodes, which led to graft loss in four cases. In all but one patient, antibodies were directed against class II or mixtures of class I and H antigens. Six patients with complications were shown to have developed de novo antibodies against DQ incompatibilities. (b) Half of the patients with a positive ELISA test at the moment of crossmatch experienced complications. Such patients are at a threefold higher risk of suffering from rejection episodes and/or graft loss than patients who are not sensitized (P<0.05, Fisher exact test). CONCLUSIONS: Because PRA-STAT is very reproducible, detects both HLA class I and II antibodies, and is not influenced by rejection therapy, we consider it an additional tool for pre- and posttransplant monitoring of kidney allograft recipients.

Antibodies↗
PubMed1996

Dynamics of donor-reactive IgG, IgA and IgM antibodies against T and B lymphocytes early after clinical kidney transplantation using flow cytometry.

Using flow cytometry, 32 kidney graft recipients were monitored retrospectively for at least 1 month to study the dynamics of serum IgG, IgA and IgM antibodies against donor T and B lymphocytes before and after transplantation. Donor spleen lymphocytes were used as targets. In the B cell cross-match, the surface immunoglobulins were blocked with an anti-human immunoglobulin antibody. A high frequency of donor-reactive antibodies was detected early after transplantation, especially when the sera were tested against B lymphocytes. Surprisingly, donor-reactive antibodies of the IgA isotype made up a substantial proportion of all antibodies detected. Within the first month after transplantation, six out of 32 patients (19%) developed IgG antibodies against donor T lymphocytes and nine out of 35 patients (28%) formed IgG antibodies against B lymphocytes. A similar situation was found for IgA antibodies: 22% of the recipients were positive for IgA antibodies against donor T lymphocytes and 34% against B lymphocytes after transplantation. Lower antibody frequencies were found for IgM antibodies (16% and 19%, respectively). From our data we conclude that for at least some of the parameters studied their individual dynamics reflect the complex immunological mechanisms occurring early after transplantation.

Antibodies, Anti-Idiotypic↗
PubMed1992

Effect of ATG prophylaxis in sensitized and non-sensitized kidney graft recipients.

In our effort to find an optimum immunosuppressive protocol for kidney transplantation we introduced two forms of ATG prophylaxis: 1. high-dose single-bolus prophylaxis (9 mg/kg) in non-sensitized patients (PRA < 5%); and 2. low-dose 8-day prophylaxis (1.5-3.0 mg/kg) in sensitized patients (PRA > 5%). A total of 204 kidney graft recipients were included in this study and treated with a triple-drug therapy (TDT). In comparison with TDT-treated controls, in sensitized patients the 8-day ATG prophylaxis resulted in a reduced rate of rejection episodes (25.5% vs 47%), an improved 1-year graft survival (82% vs 71%) and patient survival (94% vs 90%). In non-sensitized patients the high-dose single-bolus ATG prophylaxis induced a T-cell lymphopenia lasting 4 to 5 days and, in comparison with the corresponding controls, resulted in a shortened hospital stay (31.2 days vs 36.7 days), a reduced rate of rejection episodes (25.5% vs 53%), an improved 1-year graft survival (92% vs 86%) and patient survival (100% vs 94%).

Antilymphocyte Serum↗
PubMed1989

[Weil's disease, milker's fever and other leptospiroses, 1981-1987].

In The Netherlands, human leptospirosis is mainly caused by the serovars icterohaemorrhagiae and copenhageni, both of which belong to the Icterohaemorrhagiae group and originate from rats, serovars hardjo from cattle and grippotyphosa from voles. In 1981-1987, 175 cases of leptospirosis were registered. In 17 of these cases the infection was acquired outside The Netherlands. Infections caused by serovars from the Icterohaemorrhagiae group were mainly observed in the province of Zuid-Holland, hardjo infections in the province of Friesland. The number of hardjo infections increased. Hardjo also causes problems in cattle. Infections caused by serovars icterohaemorrhagiae and copenhageni were mainly associated with exposure to inland surface waters in relation with recreational or professional activities or accidents. Hardjo infections were characteristically associated with dairy farming. The incidences of all types of leptospirosis were highest in late summer and early autumn.

Agricultural Workers' Diseases↗