Clonal Proliferation of Type 2 Helper T Cells in a Man with the Hypereosinophilic Syndrome

Abstract
The hypereosinophilic syndrome is characterized by persistent eosinophilia of unknown origin often associated with the dysfunction of multiple organs as a result of tissue infiltration by eosinophils and the toxic effects of their products1. Previous studies have suggested that T lymphocytes may be involved in the induction of the syndrome through the secretion of an eosinophil differentiation factor2,3.