Flow-mediated dilation shows impaired endothelial function in patients with mastocytosis

Background: Mastocytosis is a rare disease characterized by clonal proliferation of mast cells (MCs) in different organs. Clinical manifestations of mastocytosis are mostly due to release of mediators from MCs and, in many cases, such as urticaria, flushing, angioedema, and anaphylaxis, are an expression of the biological effects of mediators on endothelial cells. Chronic secretion of mediators in patients with mastocytosis can lead to alteration of endothelial function. Objective: We sought to investigate endothelial function in patients with mastocytosis using a noninvasive technique of flow-mediated dilation (FMD). Methods: Twenty-five adult patients with indolent and advanced forms of mastocytosis and 20 healthy control subjects were enrolled in the study. Ultrasound assessment of FMD was performed by measuring changes in the diameter of the brachial artery after 5 minutes of arterial occlusion. Changes in FMD were correlated with clinical parameters and serum tryptase levels. Results: Patients with mastocytosis had lower FMD compared with healthy control subjects (P <.001). Advanced and smoldering forms showed a lower FMD compared with indolent forms (P <.001). FMD inversely correlated with age and serum tryptase levels and directly with median arterial pressure and recurrent flushing episodes. No correlation was found between FMD and osteoporosis, recurrent anaphylaxis, presence of skin lesions, and long-term antihistamine treatment. Conclusions: Endothelial dysfunction, as demonstrated by FMD reduction, is detectable in patients with mastocytosis and is more severe in patients with high tryptase levels and advanced disease. Endothelial function appears to be negatively influenced by MC proliferation rather than by the severity of mediator-related symptoms.