Low thymic output, peripheral homeostasis deregulation, and hastened regulatory T cells differentiation in children with 22q11.2 deletion syndrome.

[22q11.2 deletion syndrome]

To perform an extensive analysis of the immune status of asymptomatic children with the 22 q 11 .2 deletion syndrome , with special emphasis on the regulatory T cells (Treg ) population .Analysis of thymic function , frequency and absolute counts of immune subsets , and phenotype of Treg were performed in 10 asymptomatic children bearing the 22 q 11 .2 deletion and compared with 12 age-matched , healthy children .Children with 22 q 11 .2 deletion syndrome showed a curtailed thymic output , lower T -cell levels , and a homeostatic deregulation in the CD 4 T -cell compartment , characterized by a greater proliferative history in the naïve CD 4 T -cell subset . Treg numbers were markedly reduced in children with 22 q 11 .2 deletion syndrome , and remaining Treg showed mostly an activated phenotype .Reduced thymic output in children with 22 q 11 .2 deletion syndrome could be related with an increased proliferation in the naïve CD 4 T -cell compartment and the consequent Treg activation to ensure that T -cell expansion remains under control . Deregulated peripheral homeostasis and loss of suppressive capacity by Treg could compromise the integrity of T -cell immunity during adulthood and play a relevant role in the increased incidence of autoimmune diseases reported in patients with the 22 q 11 .2 deletion syndrome .