On the influence of age on immunity in Down's syndrome.

In 23 subjects of different ages with Down's syndrome a number of parameters of non-specific defense of humoral and of cellular immunity were investigated. While in all age groups complement factors C3, C4 and C5 as well as phagocytosis and NBT indices were in the normal range, a dysgammaglobulinaemia increasing with age with a hyperglobulinaemia of the IgG, IgA and IgD types was found, sparing immunoglobulins IgM and IgE. In addition the transformation capacity of peripheral blood lymphocytes decreased with age. This is understood as the consequence of premature aging of the thymus-dependent immune system.