title: Altered T-cell subsets and defective T-cell function in young children with Down syndrome (trisomy-21).
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.
mesh_terms: D002675:Child, Preschool; D004314:Down Syndrome / Q000097:blood / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular; D007223:Infant; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008934:Mitogens / Q000494:pharmacology; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*
chemical_list: D007376:Interleukin-2; D008934:Mitogens