Immune-endocrine status and coeliac disease in children with Down's syndrome: relationships with zinc and cognitive efficiency.

Immune defects, thyroid abnormalities, plasma zinc levels, and the presence of gastrointestinal disease were investigated in 43 children with Down's syndrome (DS). Peripheral T lymphocytes with the phenotype of helper cells or cluster of differentiation 4 (CD4) were decreased. Circulating activated T cells (CD3/HLA-DR-positive cells) and large granular lymphocytes (CD16/CD56 positive cells) were increased. Plasma levels of interleukin-6 were higher in DS children than in controls. Serum levels of thyroid-stimulating hormone were increased in DS. Coeliac disease was over-represented in the group of DS children and many of these children also showed increased serum levels of immunoglobulin-G (IgG) specific for gliadin antigen. The increment of serum interleukin-6 was age-related and correlated with anti-gliadin IgG levels in DS. Plasma zinc levels were lower in DS children with coeliac disease and in those with anti-gliadin IgG than in DS without detectable anti-gliadin IgG. Dietary antigens may represent a continuous stimulus for the immune system in this syndrome and interfere with normal immune responses. Altered intestinal absorption of nutrients may in turn affect endocrine functions, brain development, and cognitive performances.