Synergistic Actions of Histamine-Releasing Factor and Histamine Releasing Factor-Reactive IgE in Chronic Urticaria.

The etiology of chronic urticaria (CU) remains elusive. Histamine-releasing factor (HRF) is reported to have a proinflammatory role in asthma and immediate hypersensitivity of the skin. The aim of this study was to examine the role of HRF in the pathogenesis of CU. Forty patients with CU were enrolled and their serum HRF concentrations were determined by ELISA. The results demonstrated that the concentrations of HRF and HRF-reactive IgE in the CU group were significantly higher than those in the control group, and there was a significant linear correlation between HRF and HRF-reactive IgE concentrations (r = 0.859, p < 0.001) in CU patients. Additionally, the HRF-reactive IgE concentration was significantly correlated with the disease activity (r = 0.693, p < 0.0001). HRF and HRF-reactive IgE alone failed to activate LAD2 cells. After being primed by the patient sera with the highest IgE concentrations and stimulated by HRF, β-hexosaminidase can be released from LAD2 cells. Our findings suggest that the synergistic actions of HRF and HRF-reactive IgE may play important roles in the pathogenesis of CU.