Cultured peripheral blood mast cells from chronic idiopathic urticaria patients spontaneously degranulate upon IgE sensitization: Relationship to expression of Syk and SHIP-2

Recently, signaling changes in the FcRI pathway involving inositol lipid phosphatases have been identified in the basophils of chronic idiopathic urticaria (CIU) subjects. Based on the profile of basophil FcRI-mediated histamine degranulation, we have segregated CIU subjects into two groups, CIU Responder (CIU R) or CIU Nonresponder (CIU NR). In the present study, we compared expression of SHIP-1, SHIP-2, and Syk protein to histamine release (HR) from mast cells (MC) cultured from the peripheral blood of CIU R, CIU NR, and normal subjects. The MC of CIU R donors contained significantly increased Syk and decreased SHIP-2 as compared to CIU NR (Syk: p = 0.038, SHIP-2: p = 0.038) and normals (Syk: p = 0.042, SHIP-2: p = 0.027). Spontaneous HR from CIU donors was increased two-fold compared to normals (p = 0.04). In summary, our results suggest a possible predilection for urticarial MC to spontaneously degranulate upon IgE sensitization contributing to the increased pruritis associated with CIU.