Clonal Th2 lymphocytes in patients with the idiopathic hypereosinophilic syndrome

Idiopathic hypereosinophilic syndrome (HES) and Gleich's syndrome are relat ed disorders characterized by persistent or recurrent hypereosinophilia of unknown origin. Elevated IgE levels and polyclonal hypergammaglobulinaemia are considered as markers of benign outcome in this setting as they are gen erally associated with predominant cutaneous manifestations and favourable response to glucocorticoid therapy In a previous study, we identified a clo nal population of CD3(-)CD4(+) Th2-like lymphocytes secreting interleukin ( IL)-5 and IL-4 in peripheral blood of a patient fulfilling the diagnostic c riteria of HES with associated serum hyper-IgE. We now extend this observat ion by describing identical findings in three additional patients, and we c ompare their clinical and biological parameters with five other patients wi th HES. Chromosomal abnormalities were detected in purified CD3(-)CD4(+) Th 2, cells from three patients, among whom one developed anaplastic null cell lymphoma. We therefore suggest that a careful search for T-lymphocyte clon ality and cytogenetic changes should be included in the work-up of HES for adequate management.