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The Inducible Defense System: The Induction and Development of the Inducible Defence
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Michael A. Hickey, Diane Wallace Taylor
The progenitor for lymphocytes has yet to be identified, but it also develops from the multipotential stem cell. It is currently unclear how B cells, T cells, and a lymphocyte-related cell—called a natural killer (NK) cell—differentiates from the stem cell. Several theories exist for the development of these cells, but a clear progression is as yet unresolved. Because mice and humans with severe combined immune deficiency (SCID) lack both B cells and T cells, it is believed that they may derive from a single progenitor (Figure 8.4). Although NK cells share many of the cell surface markers with T cells, they are likely to be of a different lineage, since the SCID defect prevents the formation of B and T cells without effecting NK cell development.
Infection and immunology
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
5.34. For which of the following diseases can a diagnosis be made by flow cytometric analysis of lymphocyte subsets? X-linked hypogammaglobulinaemia (XLH).Severe combined immunodeficiency (SCID).diGeorgé anomaly (DGA).Leukocyte adhesion defect (LAD).Ataxia telangiectasia (AT).
Diagnosis of immune deficiency diseases
Published in Gabriel Virella, Medical Immunology, 2019
John W. Sleasman, Gabriel Virella
Newborn screening (NBS) has proven to be highly effective in identifying and treating infants with genetic conditions. It is most effective when the incidence of the condition is high (at least 1:100,000 live births) and early diagnosis has a positive effect on long-term health or survival. Almost all U.S.-born infants are screened for more than 40 congenital diseases, and HIV screening is done on all pregnant women. There is variability of the screening panel among states, as each state department of health determines the conditions for which it screens. Any abnormal results require confirmatory testing prior to a definitive diagnosis. Screening for congenital T abnormalities fits into the paradigm for a condition where screening is effective at birth. Severe combined immune deficiency (SCID) has serious morbidity or mortality as almost all infants who go undiagnosed die before 2 years of age. Early diagnosis and treatment significantly improve prognosis, as nearly 90% of infants who receive hematopoietic stem cell transplantation before 3 months of life survive. SCID is not easily detected at birth by routine physical exam, as infants appear to be normal. There is a sensitive, specific, inexpensive test that utilizes existing NBS tools (Guthrie Card) to test dried blood spots obtained from heel sticks collected at birth. If the T-cell receptor excision circles (TREC) are below the threshold of normal lymphocyte counts, enumeration is performed using flow cytometry as the confirmatory test.
Ex vivo gene therapy for lysosomal storage disorders: future perspectives
Published in Expert Opinion on Biological Therapy, 2023
Edina Poletto, Andrew Oliveira Silva, Ricardo Weinlich, Priscila Keiko Matsumoto Martin, Davi Coe Torres, Roberto Giugliani, Guilherme Baldo
However, to produce optimal results, some important issues still need to be addressed. Some of these issues are related to the availability of patients. For example, due to their low frequency and unspecific symptoms and signs, often LSD patients are diagnosed later in life, when a gene therapy procedure is less likely to produce major benefits. To solve this, early-diagnosis strategies such as newborn screening need to be considered. Other issues are related to the gene therapy procedure per se. In particular, one important point that still needs to be addressed more carefully is genotoxicity and cellular transformation, which has been shown in past gene therapy trials for other conditions, such as X-linked severe combined immunodeficiency (SCID). Even with new techniques that allow gene insertion at a more precise spot, such as genome editing systems, off target effects are still a possibility, and detecting these events when at a very low frequency can be challenging.
Gene therapy for primary immunodeficiencies: up-to-date
Published in Expert Opinion on Biological Therapy, 2021
Severe combined immunodeficiency (SCID) is the most lethal PID, comprising a group of inherited disorders with a collective prevalence of 1:58 000 live births [21]. The disease is characterized by profound impairments in T cell development and function, and depending on the molecular defect, diminished B, and NK cell activity. B cells may have an intrinsic developmental defect or be functionally impaired due to T helper cell defects, which prevent B cells from mounting a normal antibody response and lead to the combined deficits in SCID of cellular and humoral immunity [22]. The disease presents in infancy, most commonly with life-threatening opportunistic infections, failure to thrive, and chronic diarrhea and is invariably fatal in the first year of life without treatment. HSCT must be performed to restore immunological function, however transplant outcomes are affected by the presence of active infection at time of transplant, as well as the degree of HLA match of the donor [23].
Digital microfluidics comes of age: high-throughput screening to bedside diagnostic testing for genetic disorders in newborns
Published in Expert Review of Molecular Diagnostics, 2018
David Millington, Scott Norton, Raj Singh, Rama Sista, Vijay Srinivasan, Vamsee Pamula
Molecular testing is already established for second-tier testing in NBS for conditions such as cystic fibrosis, for which the primary screening test lacks specificity. It is also currently used to screen for primary immune defects, including severe combined immune deficiency (SCID), and will soon be required to screen for spinal muscular atrophy and possibly for other conditions for which a suitable biochemical test is not available. The expansion of molecular testing to whole exome sequencing from DBS is already practical, and has the potential to encompass a much wider range of heritable conditions than the current panel of recommended conditions. The obvious drawbacks to wholesale genetic screening of newborns include cost, inconclusive results, delays in interpretation and result reporting, lack of autonomy, and many other issues that raise serious ethical considerations. Similar arguments apply to other untargeted methodologies, such as metabolomics and proteomics that have been proposed to expand NBS.