Abstract
The hypereosinophilic syndrome (HES) has been previously described as a chnicobiological entity characterized by a blood eosinophil count of over 1.5 × 109L of unknown cause associated with several clinical complications. In reality, HES is a heterogeneous group or diseases with variable and unpredictable progress in visceral lesions, thought to be related to the deleterious effects of tissue eosinophil infiltration. Various criteria for discrimination between benign and severe forms of HES have been described. These previous retrospective clinical investigations, using biological and clinical markers, have defined different stages of HES. It appears more relevant, however, to consider elements of disease activity by studying mechanisms of induction of persistent hypereosinophilia. The T-cell dependence of blood eosinophilia has led us to evaluate various markers of T-cell activation in particular. In the present review, we report previous results and perspectives suggested by the study of the interleukin 2 receptor in HES.