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Biomedical subjects

Lars P Ryder

Publications and source records attributed to Lars P Ryder.

17 recordsLinked to original sources
PubMed2006

Cytokine gene expression in peripheral blood mononuclear cells and alloreactivity in hematopoietic cell transplantation with nonmyeloablative conditioning.

Cytokines are thought to play an important role in the pathophysiology of graft-versus-host disease (GVHD). To study the relationship between cytokines and GVHD, we obtained peripheral blood mononuclear cells (MNCs) from 21 patients with hematologic malignancies and their HLA-identical sibling donors before and sequentially after hematopoietic cell transplantation (HCT) with nonmyeloablative conditioning. The MNCs were cultured for 72 hours either alone or in mixed lymphocyte cultures with irradiated MNCs of recipient, donor, or HLA-mismatched third-party origin. The gene expression of interleukin (IL)-2, IL-4, IL-10, IL-18, tumor necrosis factor alpha, and transforming growth factor beta in each culture was then measured by real-time quantitative reverse transcriptase-polymerase chain reaction. The composition of the responder MNCs differed between patients and donors and changed after HCT, with a possible influence on the results. Early after transplantation (day +14), the IL-10 messenger RNA (mRNA) level in response to recipient or donor antigens was higher in patients who did not develop clinically significant acute GVHD when compared with the level in patients who subsequently developed acute GVHD grades II to IV (P = .005 and P = .004, respectively). The IL-10 mRNA level on day +14 was highly correlated with the pretransplantation mRNA level of the recipient MNCs but not with the level of the donor MNCs; this suggests that the IL-10 mRNA detected on day +14 originated from responder cells of recipient origin. A higher IL-10 mRNA level was found in MNCs obtained before transplantation from recipients whose disease progressed or relapsed after the transplantation when compared with the level in patients whose disease did not progress or relapse (P = .03). In conclusion, a high IL-10 gene expression in the recipient MNCs may be related to a reduced incidence of acute GVHD grades II to IV and a reduced graft-versus-tumor effect after HCT with nonmyeloablative conditioning.

Adult↗
PubMed2006

Variation in DNA repair genes ERCC2, XRCC1, and XRCC3 and risk of follicular lymphoma.

The reasons for the positive association between skin cancer and non-Hodgkin's lymphoma are not known but may be due to common susceptibility involving suboptimal DNA repair. Therefore, we investigated selected polymorphisms and haplotypes in three DNA repair genes, previously associated with skin cancer and DNA repair capacity, in risk of follicular lymphoma, including possible gene interaction with cigarette smoking and sun exposure. We genotyped 19 single nucleotide polymorphisms (SNP) in the ERCC2, XRCC1, and XRCC3 genes in 430 follicular lymphoma patients and 605 controls within a population-based case-control study in Denmark and Sweden. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using unconditional logistic regression and haplotype associations were assessed with a global score test. We observed no associations between variation in the ERCC2 and XRCC1 genes and follicular lymphoma risk. In XRCC3, increased risk of follicular lymphoma was suggested for rare homozygotes of three SNPs [Rs3212024: OR, 1.8 (95% CI, 1.1-2.8); Rs3212038: OR, 1.5 (95% CI, 1.0-2.4); Rs3212090: OR, 1.5 (95% CI, 1.0-2.5)]. These results were strengthened in current cigarette smokers. However, evidence of differences in XRCC3 haplotype distributions between follicular lymphoma cases and controls was weak, both overall and in current smokers. We conclude that polymorphic variation in the XRCC3 gene, but not in ERCC2 or XRCC1, may be of importance for susceptibility to follicular lymphoma, perhaps primarily in current smokers. The link between skin cancer and follicular lymphoma is unlikely to be mediated through common variation in the studied DNA repair gene polymorphisms.

Adolescent↗
PubMed2005

A high-density screen for linkage in multiple sclerosis.

To provide a definitive linkage map for multiple sclerosis, we have genotyped the Illumina BeadArray linkage mapping panel (version 4) in a data set of 730 multiplex families of Northern European descent. After the application of stringent quality thresholds, data from 4,506 markers in 2,692 individuals were included in the analysis. Multipoint nonparametric linkage analysis revealed highly significant linkage in the major histocompatibility complex (MHC) on chromosome 6p21 (maximum LOD score [MLS] 11.66) and suggestive linkage on chromosomes 17q23 (MLS 2.45) and 5q33 (MLS 2.18). This set of markers achieved a mean information extraction of 79.3% across the genome, with a Mendelian inconsistency rate of only 0.002%. Stratification based on carriage of the multiple sclerosis-associated DRB1*1501 allele failed to identify any other region of linkage with genomewide significance. However, ordered-subset analysis suggested that there may be an additional locus on chromosome 19p13 that acts independent of the main MHC locus. These data illustrate the substantial increase in power that can be achieved with use of the latest tools emerging from the Human Genome Project and indicate that future attempts to systematically identify susceptibility genes for multiple sclerosis will have to involve large sample sizes and an association-based methodology.

Australia↗
PubMed2005

A functional polymorphism in the Eta-1 promoter is associated with allele specific binding to the transcription factor Sp1 and elevated gene expression.

Early T lymphocyte activator 1 (Eta-1), also known as Osteopontin, is a cytokine produced by macrophages and T lymphocytes. It is involved in the regulation of IL-12 and IL-10 expression in macrophages and stimulates the polarization of T cells to the Th1 subset. Three promoter polymorphisms of the human Eta-1 gene, -443T/C, -156delG/G, -66T/G, were investigated for possible influence on gene expression. Electrophoretic mobility shift assays (EMSA) with nuclear extract from the human myeloid leukaemia premonocyte cell line, THP-1, revealed sequence specific binding of the transcription factor Sp1 to the -66T allele but not the -66G allele, and haplotype -443C/-156G/-66T showed a marked increase in promoter activity of a luciferase reporter gene. Thus, a substitution of the T-base with G at position -66 in the Eta-1 promoter modulates the promoter activity of the Eta-1 gene, which might influence the Th1 versus Th2 balance. These observations are discussed in relation to a recently reported related observation on the same gene, and it is argued that discrepancies between reporter gene assays in the two studies may be due to the use of different cell lines and may reflect requirements for different transcription factors in cells involved in immune responses compared with other cells.

Alleles↗
PubMed2005

Evaluation and automation of hematopoietic chimerism analysis based on real-time quantitative polymerase chain reaction.

Abstract Chimerism analysis is an essential tool in the follow-up of patients after allogeneic stem cell transplantation. High-resolution methods for chimerism analysis based on real-time quantitative polymerase chain reaction (RQ-PCR) with a detection limit of 0.1% marker-specific cells are especially valuable in the detection of patient-derived subpopulations for the monitoring of minimal residual disease. Using artificial chimeric mixtures of genotypically different cells, we optimized and evaluated the intrasample variation, accuracy, and detection limit of chimerism analysis based on RQ-PCR of short insertion and deletion polymorphisms. Furthermore, automated setup by robot was evaluated. The results were accurate, with acceptable intrasample variation at and above 0.1% marker-specific cells. The sensitivity was mainly limited by background values. Chimerism results based on RQ-PCR were similar to results based on PCR of short tandem repeats when samples from recipients of transplants with nonmyeloablative conditioning were analyzed. Furthermore, automated setup was feasible in a time-, labor-, and reagent-conserving manner.

Evaluation Studies as Topic↗
PubMed2005

Locked nucleic acid inhibits amplification of contaminating DNA in real-time PCR.

Locked nucleic acid (LNA) is a modified DNA with increased binding affinityfor complementary DNA sequences. Our strategy was to use this property of LNA to inhibit undesired PCR amplification (e.g.,from contaminating genomic DNA) in a cDNA-based assay. By placing a short complementary LNA sequence in intronic DNA, the aim was to inhibit the amplification of genomic DNA without affecting the amplification of reverse-transcribed spliced mRNA. LNA was designed to bind within intron 5 in the x-box binding protein 1 (XBP1) gene. An irrelevant LNA oligonucleotide served as a negative control. In both PCR and real-time PCR, the addition of LNA showed blocking of the amplification of genomic XBP1 but not cDNA XBP1. To test the effect of melting temperature (Tm) on the LNA, we investigated the number of LNA nucleotides that could be replaced with DNA nucleotides and still retain the blocking activity. More than three DNA nucleotides reduced the LNA inhibition ability. The sequence specificity of the LNA was tested by investigating the number of LNA nucleotide mismatches permitted. The introduction of one mismatch maintained the inhibition of genomic amplification whereas two mismatches reduced the amplification. Our results show that LNA may be used to enhance the specificity of PCR by eliminating unwanted PCR products.

Base Pair Mismatch↗
PubMed2004

Chimerism studies in HLA-identical nonmyeloablative hematopoietic stem cell transplantation point to the donor CD8(+) T-cell count on day + 14 as a predictor of acute graft-versus-host disease.

Chimerism analysis of hematopoietic cells has emerged as an essential tool in nonmyeloablative hematopoietic stem cell transplantation. We have investigated the development of donor chimerism in granulocytes and CD4(+) and CD8(+) T cells in blood and bone marrow of 24 patients with hematologic malignancies who received HLA-identical sibling peripheral blood stem cell grafts after conditioning with fludarabine and 2 Gy of total body irradiation. The T-cell chimerism of blood and bone marrow was tightly correlated. Complete donor chimerism was reached earlier in the granulocytes than in the T cells. Mixed T-cell chimerism was common at the time of onset of acute graft-versus-host disease (aGVHD), and both CD4(+) and CD8(+) donor T-cell chimerism increased with the occurrence of aGVHD grades II to IV (P =.0002 and P =.019, respectively). The rate of disappearance of recipient CD8(+) T cells was faster in patients with aGVHD grades II to IV than in patients without clinically significant aGVHD (P =.016). This observation indicates a role of graft-versus-lymphohematopoietic tissue reactions in creating complete donor T-cell chimerism. A donor CD8(+) T-cell count above the median on day +14 increased the risk of subsequent development of aGVHD grades II to IV (P =.003).

Acute Disease↗
PubMed2004

Haematopoietic stem cell transplantation with non-myeloablative conditioning in the outpatient setting: results, complications and admission requirements in a single institution.

Thirty patients with haematological malignancies received peripheral blood stem cells from human leucocyte antigen (HLA)-identical sibling donors after non-myeloablative conditioning with fludarabine and total body irradiation. Twenty-seven patients received the transplant as an outpatient procedure. All patients engrafted. The probability of acute graft-versus-host disease (GVHD) grades II-IV and extensive chronic GVHD was 57% and 80%, respectively. Patients alive on day +365 experienced a median of 44 d (range 4-151) of hospitalization during the first year. In the entire cohort, GVHD accounted for 22%, infections for 18%, thrombotic thrombocytopenic purpura (TTP) for 16% and engraftment syndrome for 14% of the time in hospital. The 1-year risk of TTP was 26%. Acute GVHD was a risk factor for the development of TTP (P = 0.008). With a median follow-up of 602 d, the 2-year estimates for overall survival, progression-free survival, non-relapse mortality and relapse related mortality were 68%, 43%, 22% and 13%, respectively. This transplantation regimen is feasible and induces long-term remissions in heavily pretreated patients. The procedure can be performed in the outpatient setting, but complications could result in a substantial number of admissions during the first year.

Adult↗
PubMed2004

Concordance for disease course and age of onset in Scandinavian multiple sclerosis coaffected sib pairs.

BACKGROUND: Investigation of coaffected sib pairs is one method to determine the genetic influence on the clinical presentation of many complex diseases, such as multiple sclerosis (MS). Investigation of the clinical concordance in coaffected sib pairs may be a prerequisite to identify genes that modify the clinical outcome. The aim of this study was to investigate a possible genetic influence on selected demographic and clinical variables among familial Scandinavian MS cases. MATERIAL AND METHODS: We identified 136 Caucasian Scandinavian families with MS coaffected sib pairs from Denmark, Norway and Sweden. Cohen's kappa coefficient and the intraclass correlation coefficient were used to assess concordances in sib pairs. Furthermore, clinical features and HLA-DR2 carrier status were compared among the probands of sib pairs. RESULTS: We found significant concordance of the disease course (kappa = 0.28, P < 0.001) and adjusted age of onset (r = 0.23, P = 0.028). Among probands of sib pairs, HLA-DR2 carrier patients had a younger age of onset (P = 0.024). CONCLUSION: Analyses of Scandinavian coaffected sib pairs suggest that disease course and age of onset are partly under genetic control. Furthermore, HLA-DR2 in probands of sib pairs suggests importance for age of onset.

Age of Onset↗
PubMed2003

CCR3 expression induced by IL-2 and IL-4 functioning as a death receptor for B cells.

We report that CCR3 is not expressed on freshly isolated peripheral and germinal B cells, but is up-regulated after stimulation with IL-2 and IL-4 (approximately 98% CCR3(+)). Ligation of CCR3 by eotaxin/chemokine ligand (CCL) 11 induces apoptosis in IL-2- and IL-4-stimulated primary CD19(+) (approximately 40% apoptotic cells) B cell cultures as well as B cell lines, but has no effect on chemotaxis or cell adhesion. Freshly isolated B cells express low levels of CD95 and CD95 ligand (CD95L) (19 and 21%, respectively). Expression is up-regulated on culture in the presence of a combination of IL-2, IL-4, and eotaxin/CCL11 (88% CD95 and 84% CD95L). We therefore propose that ligation of such newly induced CCR3 on peripheral and germinal B cells by eotaxin/CCL11 leads to the enhanced levels of CD95 and CD95L expression. Ligation of CD95 by its CD95L expressed on neigboring B cells triggers relevant death signaling pathways, which include an increase in levels of Bcl-2 expression, its functional activity, and the release of cytochrome c from the mitochondria into the cytosol. These events initiate a cascade of enzymatic processes of the caspase family, culminating in programmed cell death. Interaction between CCR3 and eotaxin/CCL11 may, besides promoting allergic reactions, drive activated B cells to apoptosis, thereby reducing levels of Ig production, including IgE, and consequently limit the development of the humoral immune response. The apoptotic action of eotaxin/CCL11 suggests a therapeutic modality in the treatment of B cell lymphoma.

Apoptosis↗
PubMed2003

Mannose-binding lectin engagement with late apoptotic and necrotic cells.

The serum opsonin mannose-binding lectin (MBL) has been shown to be involved in the handling of apoptotic cells. However, at what stage in the process this happens and whether this mediates activation of complement is unknown. Cells rendered apoptotic or necrotic were incubated with purified MBL/MBL-associated serine protease (MASP) complexes and assessed by flow cytometry and fluorescence microscopy. MBL bound specifically to late apoptotic cells, as well as to apoptotic blebs and to necrotic cells, but not to early apoptotic cells. Binding of MBL could be inhibited by EDTA as well as with an antibody against the CRD region. Addition of C1q, another serum opsonin involved in the handling of apoptotic cells, prior to MBL partly inhibited MBL binding to apoptotic cells and vice versa. MBL/MASP could initiate deposition of purified complement C4 on the target cells. However, addition of MBL/MASP to whole serum deficient for both C1q and MBL did not enhance deposition of C4, but MBL enhanced phagocytosis of apoptotic cells by macrophages. These results demonstrate that MBL interacts with structures exposed on cells rendered late apoptotic or necrotic and facilitates uptake by macrophages. Thus, MBL may promote non-inflammatory sequestration of dying host cells.

Apoptosis↗
PubMed2003

Post-induction residual disease in translocation t(12;21)-positive childhood ALL.

BACKGROUND: t(12;21)(p1 3;q22), the most frequent chromosomal translocation found in childhood acute lymphoblastic leukemia (ALL), occurs in approximately 25% of B-lineage ALL cases and has been claimed to carry a good prognosis. PROCEDURE: As part of the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL-MRD 95 study, which includes children from Iceland, Norway, and Denmark diagnose d with ALL, patients were screened for the presence of t(12; 21) by reverse transcriptase-polymerase chain reaction (RT-PCR) at diagnosis, and their residual disease was quantified after 4 weeks of induction therapy (prednisolone, vincristine, doxorubicin, i.t. methotrexate) by a competitive, clone-specific, semi-nested PCR analysis. RESULTS: Among 96 children diagnosed with ALL, and quantified for post induction residual disease, 32 were t(12;21)-positive. The median residual disease was similar for B-precursor ALL patients with and without t(12;21) (0.009 vs. 0.03%, P = 0.12). CONCLUSIONS: Al though patients with t(12;21)-positive ALL have been claimed to have a good outcome, these data indicate that this does not reflect a high sensitivity to prednisolone, vincristine, and doxorubicin given during induction therapy.

Adolescent↗
PubMed2003

Two genome-wide linkage disequilibrium screens in Scandinavian multiple sclerosis patients.

We report the first two genome-wide screens for linkage disequilibrium between putative multiple sclerosis (MS) susceptibility genes and genetic markers performed in the genetically homogenous Scandinavian population, using 6000 microsatellite markers and DNA pools of approximately 200 MS cases and 200 controls in each screen. Usable data were achieved from the same 3331 markers in both screens. Nine markers from eight genomic regions (1p33, 3q13, 6p21, 6q14, 7p22, 9p21, 9q21 and Xq22) were identified as potentially associated with MS in both screens.

Alleles↗
PubMed2002

Association between larger thymic size and higher thymic output in human immunodeficiency virus-infected patients receiving highly active antiretroviral therapy.

To examine the impact of thymic size on immune recovery in patients with human immunodeficiency virus (HIV) infection, the thymus was visualized, using computed tomographic scans, in 25 HIV-infected patients who had received highly active antiretroviral therapy (HAART) for 6-18 months and had levels of viremia <500 copies/mL. For comparison, 10 control subjects were included in the study. Total and naive CD4+ cell counts were determined by flow cytometry. To determine thymic output, the number of CD4+ cells containing T cell receptor excision circles (TRECs) was measured. Qualitative immune recovery was evaluated by determination of CD4+ T cell receptor repertoire in 19 of the HIV-infected patients. Larger thymic size was associated with higher CD4+ cell counts (r=0.498; P=.011) and higher CD4+ TREC frequency (r=0.652; P<.001). Furthermore, patients with abundant thymic tissue seemed to have broader immunologic repertoires, compared with patients with minimal thymic tissue (P=.054). These findings suggest that thymopoiesis is ongoing in the adult thymus and contributes to immune reconstitution in HIV-infected patients receiving HAART.

Adult↗
PubMed2002

Precise quantification of minimal residual disease at day 29 allows identification of children with acute lymphoblastic leukemia and an excellent outcome.

The postinduction level of minimal residual disease (MRD) was quantified with a competitive polymerase chain reaction (PCR) technique in 104 children with acute lymphoblastic leukemia (ALL) diagnosed between June 1993 and January 1998 and followed for a median of 4.2 years. A significant correlation was found between the MRD level on day 15 (D15) and day 29 (D29) after the start of induction therapy (r(s) = 0.70, P <.0001). The 15 patients with T-cell disease had higher D29 MRD than those with B-lineage ALL (P =.01). Age was positively related to D29 MRD (r(s) = 0.32, P =.001). The 16 patients who had a relapse had higher D15 and D29 MRD levels than the patients who stayed in remission (median levels D15, 1% versus 0.1%, P =.03; D29, 0.4% versus 0.01%, P =.0001). No patients with a MRD level less than 0.01% on D29 have so far had a relapse, whereas the 7-year probability of event-free survival for patients with higher MRD levels was 0.52 (P =.0007). The group of patients with a D29 MRD less than 0.01% included patients with T-cell disease, white blood cell count more than 50 x 10(9)/L at diagnosis, or age 10 years or older, and could not be identified by up-front criteria. The best-fit Cox model to predict the risk of relapse included D29 MRD (P =.004) and age (P =.009). These findings indicate that with the present treatment protocol MRD quantification at an early stage of therapy identifies patients with a very low risk of relapse. Further trials are needed to reveal whether such patients with D29 MRD less than 0.01% can be cured with less intensive chemotherapy, which would reduce the risk of serious late effects as well as the costs of therapy.

Adolescent↗
PubMed2002

Thymic involvement in immune recovery during antiretroviral treatment of HIV infection in adults; comparison of CT and sonographic findings.

In adult HIV-infected patients, thymic size evaluated from CT scans seems to be important to the degree of immune reconstitution obtainable during treatment with highly active antiretroviral therapy (HAART). To examine whether ultrasound is as reliable as CT for estimating thymic size and predicting immune recovery, CT and ultrasound scans were performed in 25 adult HIV-infected patients and 10 controls. CD4 counts and naive CD4 counts were measured in order to determine immune reconstitution. Furthermore, the CD4+ T-cell receptor excision circle (TREC) frequency and T-cell receptor (TCR) repertoire were determined. The study demonstrated no correlation between the 2 scanning methods (r = 0.201, p = 0.358 in patients and r = 0.457, p = 0.184 in controls). Among the patients, no association was found between the sonographically estimated thymic size and immunological parameters such as CD4 count (r = 0.083, p = 0.706), naive CD4 count (r = 0.067, p = 0.762), CD4 + TREC frequency (r = 0.028, p = 0.900) and CD4 + TCR repertoire (r = -0.057, p = 0.828). These findings show that CT remains superior for assessing thymic size in adults and is preferable to ultrasound when evaluating the importance of a large thymus to immune recovery during HAART.

Adult↗