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B lymphocytes are key players in humoral immunity, expressing diverse surface immunoglobulin receptors directed against specific antigenic epitopes. The development and profile of distinct subpopulations have gained awareness in the setting of primary immunodeficiency disorders, primary or secondary autoimmunity and as therapeutic targets of specific antibodies in various diseases. The major B cell subpopulations in peripheral blood include naïve (CD19+ or CD20+IgD+CD27−), non-switched memory (CD19+ or CD20+IgD+CD27+) and switched memory B cells (CD19+ or CD20+IgD−CD27+). Furthermore, less common B cell subpopulations have also been described as having a role in the suppressive capacity of B cells to maintain self-tolerance. Data on reference values for B cell subpopulations are limited and only available for older age groups, neglecting the continuous process of human B cell development in children and adolescents. This study was designed to establish an exponential regression model to produce continuous reference values for main B cell subpopulations to reflect the dynamic maturation of the human immune system in healthy children.
Natural killer (NK) cells play an important role following allogeneic hematopoietic stem cell transplantation (HSCT) exerting graft-versus-leukemia/tumor effect and mediating pathogen-specific immunity. Although NK cells are the first donor-derived lymphocytes reconstituting post-HSCT, their distribution of CD56++CD16− (CD56bright), CD56++CD16+ (CD56intermediate=int), and CD56+CD16++ (CD56dim) NK cells is explicitly divergent from healthy adults, but to some extent comparable to the NK cell development in early childhood. The proportion of CD56bright/CD56int/CD56dim changed from 15/8/78% in early childhood to 6/4/90% in adults, respectively. Within this study, we first compared the NK cell reconstitution post-HSCT to reference values of NK cell subpopulations of healthy children. Afterward, we investigated the reconstitution of NK cell subpopulations post-HSCT in correlation to acute graft versus host disease (aGvHD) and chronic graft versus host disease (cGvHD) as well as to viral infections. Interestingly, after a HSCT follow-up phase of 12 months, the distribution of NK cell subpopulations largely matched the 50th percentile of the reference range for healthy individuals. Patients suffering from aGvHD and cGvHD showed a delayed reconstitution of NK cells. Remarkably, within the first 2 months post-HSCT, patients suffering from aGvHD had significantly lower levels of CD56bright NK cells compared to patients without viral infection or without graft versus host disease (GvHD). Therefore, the amount of CD56bright NK cells might serve as an early prognostic factor for GvHD development. Furthermore, a prolonged and elevated peak in CD56int NK cells seemed to be characteristic for the chronification of GvHD. In context of viral infection, a slightly lower CD56 and CD16 receptor expression followed by a considerable reduction in the absolute CD56dim NK cell numbers combined with reoccurrence of CD56int NK cells was observed. Our results suggest that a precise analysis of the reconstitution of NK cell subpopulations post-HSCT might indicate the occurrence of undesired events post-HSCT such as severe aGvHD.values
Background: Ataxia-telangiectasia (A-T) is a multisystem disorder with progressive cerebellar ataxia, immunodeficiency, chromosomal instability, and increased cancer susceptibility. Cellular immunodeficiency is based on naïve CD4+ and CD8+ T-cell lymphopenia. Hematopoietic stem cell transplantation (HSCT) offers a potential to cure immunodeficiency and cancer due to restoration of the lymphopoietic system. The aim of this investigation was to analyze the effect of HSCT on naïve CD4+ as well as CD8+ T-cell numbers in A-T.
Methods: We analyzed total numbers of peripheral naïve (CD45RA+CD62L+) and memory (CD45RO+CD62L−) CD4+ and CD8+ T-cells of 32 A-T patients. Naïve (CD62LhighCD44low) and memory (CD62LlowCD44high) T-cells were also measured in Atm-deficient mice before and after HSCT with GFP-expressing bone marrow derived hematopoietic stem cells. In addition, we analyzed T-cells in the peripheral blood of two A-T patients after HLA-identic allogeneic HSCT.
Results: Like in humans, naïve CD4+ as well as naïve CD8+ lymphocytes were decreased in Atm-deficient mice. HSCT significantly inhibited thymic lymphomas and increased survival time in these animals. Donor cell chimerism increased up to more than 50% 6 months after HSCT accompanied by a significant increase of naïve CD4 and CD8 T-cell subpopulations, but not of memory T-cells. This finding was also identified in the blood of the A-T patients after HSCT.
Conclusion: HSCT seems to be a feasible strategy to overcome immunodeficiency and might be a conceivable strategy to avoid T-cell driven cancer in A-T at higher risk for malignancy. Naïve CD4 and CD8 T-cells counts are suitable markers for monitoring immune reconstitution post-HSCT. However, risks and benefits of HSCT in A-T have to be properly weighted.
Ataxia telangiectasia (A-T) is a primary immunodeficiency with mutations in the gene encoding the A-T mutated (ATM) protein that interacts with immune, hematopoietic, and endocrine targets resulting in broad multi-systemic clinical manifestations with a devastating outcome. Apart from a progressive neurodegenerative disorder, A-T leads to significantly increased susceptibility to malignancies. It is a matter of discussion whether pre-emptive allogeneic hematopoietic stem cell transplantation (alloHSCT) using a reduced intensity conditioning regimen would be an option to restore immune-competence and prevent malignancy, as shown in animal models, because conventional treatment protocols of malignant diseases using radio- and/or chemotherapy have a high rate of therapy-related morbidity and mortality in these patients. We present the course of the disease, including immune reconstitution and neurological outcome following pre-emptive alloHSCT in a 4-year-old boy with A-T on a 6 year follow-up. Our manuscript provides a proof-of-concept of alloHSCT as an individual pre-emptive treatment strategy from which some A-T patients might benefit.
Monitoring of minimal residual disease (MRD) or chimerism may help guide pre-emptive immunotherapy (IT) with a view to preventing relapse in childhood acute lymphoblastic leukemia (ALL) after transplantation. Patients with ALL who consecutively underwent transplantation in Frankfurt/Main, Germany between January 1, 2005 and July 1, 2014 were included in this retrospective study. Chimerism monitoring was performed in all, and MRD assessment was performed in 58 of 89 patients. IT was guided in 19 of 24 patients with mixed chimerism (MC) and MRD and by MRD only in another 4 patients with complete chimerism (CC). The 3-year probabilities of event-free survival (EFS) were .69 ± .06 for the cohort without IT and .69 ± .10 for IT patients. Incidences of relapse (CIR) and treatment-related mortality (CITRM) were equally distributed between both cohorts (without IT: 3-year CIR, .21 ± .05, 3-year CITRM, .10 ± .04; IT patients: 3-year CIR, .18 ± .09, 3-year CITRM .13 ± .07). Accordingly, 3-year EFS and 3-year CIR were similar in CC and MC patients with IT, whereas MC patients without IT experienced relapse. IT was neither associated with an enhanced immune recovery nor an increased risk for acute graft-versus-host disease. Relapse prevention by IT in patients at risk may lead to the same favorable outcome as found in CC and MRD-negative-patients. This underlines the importance of excellent MRD and chimerism monitoring after transplantation as the basis for IT to improve survival in childhood ALL.
Patients with ataxia-telangiectasia (A-T) suffer from progressive cerebellar ataxia, immunodeficiency, respiratory failure, and cancer susceptibility. From a clinical point of view, A-T patients with IgA deficiency show more symptoms and may have a poorer prognosis. In this study, we analyzed mortality and immunity data of 659 A-T patients with regard to IgA deficiency collected from the European Society for Immunodeficiencies (ESID) registry and from 66 patients with classical A-T who attended at the Frankfurt Goethe-University between 2012 and 2018. We studied peripheral B- and T-cell subsets and T-cell repertoire of the Frankfurt cohort and survival rates of all A-T patients in the ESID registry. Patients with A-T have significant alterations in their lymphocyte phenotypes. All subsets (CD3, CD4, CD8, CD19, CD4/CD45RA, and CD8/CD45RA) were significantly diminished compared to standard values. Patients with IgA deficiency (n = 35) had significantly lower lymphocyte counts compared to A-T patients without IgA deficiency (n = 31) due to a further decrease of naïve CD4 T-cells, central memory CD4 cells, and regulatory T-cells. Although both patient groups showed affected TCR-ß repertoires compared to controls, no differences could be detected between patients with and without IgA deficiency. Overall survival of patients with IgA deficiency was significantly diminished. For the first time, our data show that patients with IgA deficiency have significantly lower lymphocyte counts and subsets, which are accompanied with reduced survival, compared to A-T patients without IgA deficiency. IgA, a simple surrogate marker, is indicating the poorest prognosis for classical A-T patients. Both non-interventional clinical trials were registered at clinicaltrials.gov 2012 (Susceptibility to infections in ataxia-telangiectasia; NCT02345135) and 2017 (Susceptibility to Infections, tumor risk and liver disease in patients with ataxia-telangiectasia; NCT03357978)
Ataxia-telangiectasia (A-T) is a hereditary immune system disorder with neurodegeneration. Its first neurologic symptoms include ataxic gait in early childhood, with slowly progressive cerebellar ataxia, oculomotor apraxia, oculocutaneous telangiectasia, and progressive muscle weakness. Neonatal screening for severe T-cell deficiency was recently found to diagnose A-T patients with a significantly reduced naïve T-cell pool. Our study includes 69 A-T patients between 8 January 2002 and 1 December 2019. Nineteen cases of cancer were diagnosed in 17 patients (25%), with a median overall survival [OS; 95% cumulative indcidence (CI)] of 26·9 years for the entire cohort. The 15-year OS of 82·5% (72–95%) was significantly decreased among A-T patients with malignancies, who had a median OS of 2·11 years, with a two-year-estimated OS of 50·7% (31–82%). Haematological malignancies were the major causes of death within the initial years of life with a 15 times increased risk for death [HR (95% CI): 6·9 (3·1–15.2), P < 0·001] upon malignancy diagnosis. Male patients with A-T are at a higher cancer risk than their female counterparts. This manuscript highlights the need for cancer surveillance and prevention, as well as optimal treatment in this cohort.