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Intrinsic abnormalities of lymphocyte counts in children with down syndrome
Yvette C M de Hingh1, Petrus W van der Vossen, Eugenie F A Gemen
1Laboratory of Clinical Chemistry & Hematology and Department of Pediatrics, Je-roen Bosch Hospital, 's-Hertogenbosch, The Netherlands.
Insights
Children with Down syndrome (DS) have significantly reduced T and B lymphocyte expansion, indicating an intrinsic immune system disturbance. This B lymphocytopenia persists, contributing to increased health risks in DS.
Area of Science:
- Immunology
- Genetics
- Pediatrics
Background:
- Down syndrome (DS) is linked to higher rates of infections, cancers, and autoimmune conditions.
- Immunodeficiency is a key factor in DS morbidity and mortality.
- Understanding lymphocyte population dynamics in DS is crucial.
Purpose of the Study:
- To determine absolute counts of major lymphocyte populations in children with DS.
- To investigate the immunodeficiency associated with Down syndrome.
Main Methods:
- Analyzed absolute lymphocyte subpopulation counts in 96 children with DS.
- Utilized 3-color immunophenotyping with the lysed whole-blood method.
- Compared results to healthy children without DS.
Main Results:
- The typical early-life expansion of T and B lymphocytes was severely reduced in children with DS.
- T-lymphocyte counts approached normal levels over time.
- B-lymphocyte counts remained significantly low, with most falling below normal percentiles.
Conclusions:
- Diminished T and B lymphocyte expansion suggests an intrinsic adaptive immune system defect in DS.
- This defect is not due to premature aging.
- While thymic issues may affect T cells, they don't explain the severe B lymphocytopenia in DS.
Objective:
Down syndrome (DS) is associated with an increased frequency of infections, hematologic malignancies, and autoimmune diseases, suggesting that immunodeficiency is an integral part of DS that contributes significantly to the observed increased morbidity and mortality. We determined the absolute counts of the main lymphocyte populations in a large group of DS children to gain further insight into this immunodeficiency.
Study Design:
In a large group of children with DS (n = 96), the absolute numbers of the main lymphocyte subpopulations were determined with 3-color immunophenotyping using the lysed whole-blood method. The results were compared with previously published data in healthy children without DS.
Results:
In healthy children with DS, the primary expansion of T and B lymphocytes seen in healthy children without DS in the first years of life was severely abrogated. The T- lymphocyte subpopulation counts gradually reached more normal levels with time, whereas the B- lymphocyte population remained severely decreased, with 88% of values falling below the 10th percentile and 61% below the 5th percentile of normal.
Conclusions:
The diminished expansion of T and B lymphocytes strongly suggests that a disturbance in the adaptive immune system is intrinsically present in DS and is not a reflection of precocious aging. Thymic alterations have been described in DS that could explain the decreased numbers of T lymphocytes, but not the striking B lymphocytopenia, seen in these children.
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