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  • 1
    In: Blood, American Society of Hematology, Vol. 94, No. 4 ( 1999-08-15), p. 1183-1191
    Abstract: Screening of antibodies to hepatitis C virus (HCV) is widely used for monitoring the prevalence of HCV infections and to assess HCV infectivity. Among HCV-infected individuals in the general population, the interval between the detection of HCV RNA and the development of HCV antibodies is usually 5 to 6 weeks, but in rare cases, seroconversion may be prolonged up to 6 to 9 months. In this study, we tested for the presence of HCV RNA during the antibody-undetectable period of 19 drug-injecting HCV seroconverters to gain insight into the antibody-negative carrier status in this population. HCV seroconversion status was determined by testing the first and last serum samples obtained from each subject, using third-generation antibody screening and confirmation assays. Serial samples were tested for HCV-specific antibodies to establish the moment of seroconversion and HCV RNA by single reverse transcriptase-polymerase chain reaction (RT-PCR) and branched DNA assay (bDNA) in serum. Plasma and peripheral blood mononuclear cells (PBMCs) were independently collected and tested for HCV RNA. HCV RNA-positivity was confirmed by Southern blot hybridization and sequencing of serial samples. The 19 HCV seroconverters had a mean follow-up of 5 years (range, 1 to 8 years). Of the 19, 4 were human immunodeficiency virus (HIV)-infected before HCV seroconversion. HCV RNA was detected in serum before seroconversion in 12 (63.2%) of the 19 HCV seroconverters, independent of HIV status. In 7 of these 12, the antibody-undetectable period was relatively short (2 to 10 months). The other 5, who were all HIV-negative before HCV seroconversion, had intermittent low levels of HCV RNA before seroconversion for a period of more than 12 months, with a mean of 40.8 months (range, 13 to 94 months). In all 5 individuals, independent repeats of the experiments confirmed the presence of HCV RNA in serum, and in 3 of these individuals, HCV-positivity was confirmed in independently collected plasma and PBMC samples. Low levels of HCV RNA may be present during prolonged antibody-undetectable periods before seroconversion in a number of injecting drug users. Independent of HIV status, their immune system appears to be unable to respond to these low HCV RNA levels and was sometimes only activated after reinfections with distinct HCV genotypes. These results indicate that primary HCV infection may not always elicit the rapid emergence of HCV antibodies and suggests that persistent low levels of HCV RNA (regardless of the genotype) may not elicit at all or delay antibody responses for prolonged periods of time.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1999
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 2
    In: Blood, American Society of Hematology, Vol. 94, No. 4 ( 1999-08-15), p. 1183-1191
    Abstract: Screening of antibodies to hepatitis C virus (HCV) is widely used for monitoring the prevalence of HCV infections and to assess HCV infectivity. Among HCV-infected individuals in the general population, the interval between the detection of HCV RNA and the development of HCV antibodies is usually 5 to 6 weeks, but in rare cases, seroconversion may be prolonged up to 6 to 9 months. In this study, we tested for the presence of HCV RNA during the antibody-undetectable period of 19 drug-injecting HCV seroconverters to gain insight into the antibody-negative carrier status in this population. HCV seroconversion status was determined by testing the first and last serum samples obtained from each subject, using third-generation antibody screening and confirmation assays. Serial samples were tested for HCV-specific antibodies to establish the moment of seroconversion and HCV RNA by single reverse transcriptase-polymerase chain reaction (RT-PCR) and branched DNA assay (bDNA) in serum. Plasma and peripheral blood mononuclear cells (PBMCs) were independently collected and tested for HCV RNA. HCV RNA-positivity was confirmed by Southern blot hybridization and sequencing of serial samples. The 19 HCV seroconverters had a mean follow-up of 5 years (range, 1 to 8 years). Of the 19, 4 were human immunodeficiency virus (HIV)-infected before HCV seroconversion. HCV RNA was detected in serum before seroconversion in 12 (63.2%) of the 19 HCV seroconverters, independent of HIV status. In 7 of these 12, the antibody-undetectable period was relatively short (2 to 10 months). The other 5, who were all HIV-negative before HCV seroconversion, had intermittent low levels of HCV RNA before seroconversion for a period of more than 12 months, with a mean of 40.8 months (range, 13 to 94 months). In all 5 individuals, independent repeats of the experiments confirmed the presence of HCV RNA in serum, and in 3 of these individuals, HCV-positivity was confirmed in independently collected plasma and PBMC samples. Low levels of HCV RNA may be present during prolonged antibody-undetectable periods before seroconversion in a number of injecting drug users. Independent of HIV status, their immune system appears to be unable to respond to these low HCV RNA levels and was sometimes only activated after reinfections with distinct HCV genotypes. These results indicate that primary HCV infection may not always elicit the rapid emergence of HCV antibodies and suggests that persistent low levels of HCV RNA (regardless of the genotype) may not elicit at all or delay antibody responses for prolonged periods of time.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1999
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
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  • 3
    In: Blood, American Society of Hematology, Vol. 138, No. Supplement 1 ( 2021-11-05), p. 2293-2293
    Abstract: Introduction Together with considerable improvement in diagnostics and supportive care measures, treatment intensification has contributed to the improvement of pediatric acute myeloid leukemia (AML) survival outcomes. However, treatment-related toxicity is a consequence of intensified chemotherapy regimens, which has profound implications for both morbidity and mortality. Despite the known devastating impact of all types of toxicity on quality of life (QoL), studies presenting the different forms of non-infectious toxicity prevalent during the most recent Dutch pediatric AML protocols are lacking given that only prior protocols have been evaluated in this manner as of yet. Furthermore, the literature on non-infectious toxicity incidence in pediatric AML patients is relatively scarce. Therefore, the objectives of this study were to: 1) evaluate the cumulative incidence (C.I.) of severe, but non-lethal, non-infectious toxicity during AML treatment according to the last three consecutive protocols of the Dutch Childhood Oncology Group (DCOG), and 2) compare treatment-related toxicity frequencies between protocols. Methods A retrospective chart review was performed on 245 Dutch patients diagnosed with de novo AML (acute promyelocytic leukemia, myeloid leukemia of Down Syndrome, and secondary AML were excluded) and treated according to ANLL-97/AML-12 (1998-2005) n=118, AML-15 (2005-2010) n=60, or DB-AML-01 (2010-2013) n=67. Table 1 details protocol specifics, including drug dosages per course. Grade 3-4 toxicities, including hematological toxicity, cardiotoxicity, respiratory toxicity, mucositis, typhlitis, nephrotoxicity, hepatotoxicity, neurotoxicity, pain, allergic anaphylactic reaction, and elevation of alanineaminotransferase or bilirubin were defined according to Common Terminology Criteria for Adverse Event version 4.0, excluding infectious toxicity. Grade 5 toxicity (treatment-related mortality) was beyond the scope of this study. Intensive care unit (ICU) admission data was additionally assessed. Toxicity C.I.s were determined via competing events analyses. Relapse and death were considered competing events. Patients were censored at time of stem cell transplantation. Per-protocol comparisons were conducted via Chi-square test, due to lack of sufficient power required to calculate C.I.s. Results Median age at diagnosis was 6.0 years [interquartile range (IQR) 1.0-12.0], 58% were male. Mucositis was the most frequent form of non-hematological toxicity with a C.I. of 86.1% (standard error (S.E.) 3.5%), followed by hepatotoxicity (C.I. 27.4%, S.E. 2.9%), and respiratory toxicity (C.I. 24.6%, S.E. 3.0%) (Table 2). Eighty-three patients (C.I. 33.9%, S.E. 3.0%) were admitted to the ICU at least once, for a median of 6.0 days [IQR 2.0-15.0] (Table 2). Relatively more blood transfusions (both erythrocyte and thrombocyte) were administered to patients treated according to AML-15 (98.3%) and DB-AML-01 (97.0%) compared to AML-12 (86.4%) (p=0.01 and p=0.02, respectively). Relatively more patients suffered from severe mucositis during DB-AML-01 compared to AML-12 (43.4% vs. 25.4%, p=0.01). More patients treated according to AML-15 had bilirubin levels & gt;3x upper limit of normal (ULN) compared to those treated according to AML-12 (13.3% vs. 3.4%, p=0.01). There were no differences in non-infectious toxicity frequency between AML-15 and DB-AML-01. Other forms of toxicity did not differ significantly between protocols. The percentage of patients admitted to the ICU at least once during treatment was 33.9% in AML-12, 26.7% in AML-15, and 40.3% in DB-AML-01. Conclusions The high incidence of severe short- and long-term toxicities during pediatric AML therapy poses substantial challenges for patients, families, and care providers. Mucositis was the most common form of non-hematological, non-infectious toxicity in the whole cohort and across all Dutch protocols. Toxicities were more prevalent during the more recent protocols (AML-15 and DB-AML-01) compared to AML-12. Therefore, our findings are important in that they substantiate the need to optimize pediatric AML care in a manner which decreases treatment-related toxicity and QoL impairment. High treatment-related morbidity rates stress the urge to improve supportive care and develop less toxic treatment, while maintaining efficacy. Figure 1 Figure 1. Disclosures Zwaan: Sanofi: Consultancy.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2021
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 4
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 153-153
    Abstract: Previous studies indicate unrelated donor bone marrow transplantation mismatched at HLA-C locus (antigen-level but not allele-level) result in higher acute graft-versus-host disease (GVHD) and mortality. Hematopoietic recovery is not affected by mismatching at this locus. The current selection of cord blood units is based on antigen-level HLA typing at HLA A and B and allele-level at DRB1. The relative importance of matching at HLA-C has not yet been described for unrelated UCBT. To address this question we analyzed hematopoietic recovery, acute GVHD and mortality in 619 UCBT recipients who received a single cord blood (CB) unit, a myeloablative preparative regimen and a calcinuerin inhibitor for GVHD prophylaxis. Eighty-three percent of patients received UCBT for leukemia or lymphoma and 17% for immunologic, metabolic or histiocytic diseases. Seventy percent of patients were ≤16 years of age at transplantation. HLA typing (using molecular methods) was performed for 96% (n=593) of donor-recipient pairs. Method of typing is not available for the remaining 4% (n=26). For all analysis, donor-recipient HLA matching was evaluated at the antigen-level (first 2 of 4 digits) for HLA-A, B, C and allele-level (4 digits) for DRB1. The median infused cell dose was 4 × 107/kg and median follow-up, 2 years. We first examined the effect of donor-recipient HLA matching and cell dose on hematopoietic recovery and mortality considering the current standard for selection of cord blood units. Fifteen percent (n=94) were matched at HLA A, B and DRB1, with 43% (n=265) mismatched at 1-locus and 42% (n=260) mismatched at 2-loci. As reported previously, compared to matched UCBT, neutrophil recovery at day-42 was lower after UCBT mismatched at 1-locus (RR 0.48, p=0.042) and 2-loci (RR 0.38, p=0.007). After adjusting for infused cell dose, year of transplant and disease status, platelet recovery and 1-year mortality rates were not different after matched and mismatched UCBT. We then examined whether the addition of another mismatch at the C locus impacted outcomes. The Table below shows the probabilities of hematopoietic recovery, acute GVHD and survival considering matching at the C-locus in addition to the standard criteria used for CB unit selection. The comparison groups for each of the categories below are patients who received UCBT matched at the C locus for the respective category. In conclusion, the data shown suggest HLA-C does not affect hematopoietic recovery, acute GVHD and 1-year overall survival after UCBT. However, definitive conclusions can only be achieved in a larger series. In the mean time, cord blood unit selection need not consider matching at the C-locus. Outcomes Probability p-value Neutrophil recovery at day-42 Matched at A, B, DRB1 + mismatch at C (n=22) vs. matched at C (n=72) 82% vs. 93% 0.24 1-locus mismatch at A, B, DRB1 + mismatch at C (n=162) vs. matched at C (n=103) 81% vs. 85% 0.34 2-loci mismatch at A, B, DRB1 + mismatch at C (n=217) vs. matched at C (n=43) 77% vs. 77% 0.98 Platelet recovery at day-100 Matched at A, B, DRB1 + mismatch at C (n=22) vs. matched at C (n=72) 72% vs. 68% 0.68 1-locus mismatch at A, B, DRB1 + mismatch at C (n=162) vs. matched at C (n=103) 61% vs. 66% 0.35 2-loci mismatch at A, B, DRB1 + mismatch at C (n=217) vs. matched at C (n=43) 54% vs. 58% 0.59 Acute grade 2–4 GVHD at day-100 Matched at A, B, DRB1 + mismatch at C (n=21) vs. matched at C (n=71) 32% vs. 40% 0.48 1-locus mismatch at A, B, DRB1 + mismatch at C (n=162) vs. matched at C (n=101) 36% vs. 42% 0.39 2-loci mismatch at A, B, DRB1 + mismatch at C (n=213) vs. matched at C (n=43) 35% vs. 40% 0.61 Overall survival at 1-year Matched at A, B, DRB1 + mismatch at C (n=22) vs. matched at C (n=72) 55% vs. 59% 0.74 1-locus mismatch at A, B, DRB1 + mismatch at C (n=162) vs. matched at C (n=103) 57% vs. 59% 0.74 2-loci mismatch at A, B, DRB1 + mismatch at C (n=217) vs. matched at C (n=43) 52% vs. 53% 0.89
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 5
    In: Blood Advances, American Society of Hematology, Vol. 6, No. 7 ( 2022-04-12), p. 2156-2166
    Abstract: Anti-CD20 antibodies such as rituximab are broadly used to treat B-cell malignancies. These antibodies can induce various effector functions, including immune cell-mediated antibody-dependent cellular cytotoxicity (ADCC). Neutrophils can induce ADCC toward solid cancer cells by trogoptosis, a cytotoxic mechanism known to be dependent on trogocytosis. However, neutrophils seem to be incapable of killing rituximab-opsonized B-cell lymphoma cells. Nevertheless, neutrophils do trogocytose rituximab-opsonized B-cell lymphoma cells, but this only reduces CD20 surface expression and is thought to render tumor cells therapeutically resistant to further rituximab-dependent destruction. Here, we demonstrate that resistance of B-cell lymphoma cells toward neutrophil killing can be overcome by a combination of CD47-SIRPα checkpoint blockade and sodium stibogluconate (SSG), an anti-leishmaniasis drug and documented inhibitor of the tyrosine phosphatase SHP-1. SSG enhanced neutrophil-mediated ADCC of solid tumor cells but enabled trogoptotic killing of B-cell lymphoma cells by turning trogocytosis from a mechanism that contributes to resistance into a cytotoxic anti-cancer mechanism. Tumor cell killing in the presence of SSG required both antibody opsonization of the target cells and disruption of CD47-SIRPα interactions. These results provide a more detailed understanding of the role of neutrophil trogocytosis in antibody-mediated destruction of B cells and clues on how to further optimize antibody therapy of B-cell malignancies.
    Type of Medium: Online Resource
    ISSN: 2473-9529 , 2473-9537
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2022
    detail.hit.zdb_id: 2876449-3
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