IGHE and triple-A syndrome: To examine the role of IgE in AAA, human vascular smooth muscle cells (HSMC), a cell type widely used to study AAA in vitro [3], were treated with different concentrations of IgE (0, 5, 10, 15 μg/ml), and for different periods in the indicated time courses with 10μg/ml IgE which was the optimal concentration shown in the concentration curve (Fig. 3A).