Clonal T-helper lymphocytes and elevated IL-5 levels in episodic Angioedema and eosinophilia (Gleich's syndrome)

A patient with marked chronic eosinophilia and episodic angioedema (Gleich's syndrome) with a concomitant clonal proliferation of helper T-lymphocytes is described. This association has not previously been documented. The symptoms and clinical course differ markedly from the idiopathic hypereosinophilic syndrome, including an absence of end organ involvement. However, the disease appears to have a similar pathogenesis, with elevated levels of the eosinophil-specific cytokine interleukin-5 (IL-5) produced by the T-cell clone.