CD3+/CD30+ circulating T lymphocytes are markedly increased in older subjects with Down's syndrome (Trisomy 21).

CD3+/CD30+ circulating T lymphocytes were found to be increased in the blood of individuals with Down's syndrome (DS; trisomy 21). This finding appears to be related to age as the numbers of CD3+/CD30+ T cells were dramatically enhanced in the circulation of older DS subjects. Since CD30 antigen expression is considered to be a marker of T-helper-2 (Th-2) activation, and Th-2+ cells are associated with certain human pathologies, our data may in some way explain the enhanced susceptibility of DS patients to infections, malignant diseases and autoimmunity.