Effect of imatinib mesylate therapy on serum cytokine and IgE levels in patients with MHES. Serum levels of IL-8 (A), IgE (B), IFN-λ (C), and TNF-α (D) measured before treatment and after 1 month of imatinib mesylate therapy are shown for 6 patients with MHES. Serum IL-8 values for 5 healthy blood bank donors are also shown to illustrate the increased baseline IL-8 values in patients with MHES. Whereas serum IL-8, IFN-λ, and TNF-α levels decreased in response to imatinib mesylate therapy, IgE levels rose in all patients studied.