Immune dysfunction in Down's syndrome: primary immune deficiency or early senescence of the immune system?

Multiple immunologic disturbances are commonly observed in individuals with Down's syndrome including abnormal proportions of peripheral blood lymphoid subsets, cellular dysfunction, and autoimmune phenomena. However, a majority of the individuals with this syndrome do not show clear features of immunological disease. Many of these immunological alterations are age-related changes and can be enclosed in the spectrum of multiple signs of early senescence characteristic of Down's syndrome.