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Altered T-cell subsets and defective T-cell function in young children with Down syndrome (trisomy-21)
1Department of Biology, Utah State University, Logan 84322-6800.
Insights
Children with Down syndrome (DS) experience more infections due to fewer helper T cells (OKT4+). Their immune systems show impaired responses, suggesting issues with interleukin-2 (IL-2) signaling rather than production.
Area of Science:
- Immunology
- Pediatrics
- Genetics
Background:
- Children with Down syndrome (DS) have a higher risk of severe infections, especially in early childhood.
- Limited research exists on the immune system function in young children with DS.
- Understanding immune defects is crucial for managing health in DS.
Purpose of the Study:
- To investigate the immune cell profiles and function in young children with Down syndrome.
- To compare peripheral blood mononuclear cells (PBMC) from children with DS to age-matched controls.
- To identify specific immune system deficiencies contributing to increased infection susceptibility in DS.
Main Methods:
- Studied peripheral blood mononuclear cells (PBMC) from non-institutionalized children under 6 years old.
- Compared PBMC from children with Down syndrome (DS) to age-matched healthy controls.
- Assessed T cell populations (OKT4+, OKT8+), T cell proliferation responses, and interleukin-2 (IL-2) production.
Main Results:
- Children with DS showed reduced numbers of circulating helper T cells (OKT4+) and a lower OKT4+/OKT8+ ratio.
- PBMC from DS subjects had diminished proliferative responses to certain mitogens (phytohemagglutinin, optimal Con A).
- Normal interleukin-2 (IL-2) production was observed in PBMC from young children with DS.
Conclusions:
- The primary immune defect in Down syndrome involves a reduced number and function of helper T cells.
- Interleukin-2 (IL-2) production may be intact, but the cellular response to IL-2 might be impaired in DS.
- These findings highlight specific immune system vulnerabilities in young children with Down syndrome, impacting their infection risk.
Abstract:
Children with Down syndrome (DS) suffer an increased incidence of severe viral and bacterial infections particularly during the first 5 years of life. Unfortunately, few studies have been performed on the immune systems of young children with Down syndrome. Peripheral blood mononuclear cells (PBMC) from a group of non-institutionalized children less than 6 years of age were studied and compared with PBMC from age-matched controls. The children with DS had reduced numbers of circulating OKT4+ (helper/inducer) T cells and a significantly depressed ratio of OKT4+ to OKT8+ (suppressor/cytotoxic) T cells. PBMC from the DS subjects exhibited reduced proliferative responses to phytohemagglutinin and to an optimal concentration of concanavalin A (Con A), but normal responses to suboptimal doses of Con A and pokeweek mitogen. PBMC from young children with DS appeared to produce normal levels of interleukin-2 (IL-2). These findings provide evidence that the primary immune defect in DS is in part a depressed number and function of helper T cells. They also indicate that IL-2 production may not be defective in DS, but rather that the mechanism for response to IL-2 may be faulty.