577 CD63 Expression, IL3 Receptor, IGG Autoantibody and Autologous Serum Skin Test Accuracy in Patients with Chronic Urticaria in Brazil

BACKGROUND: Recently, a laboratory technique called basophil activation test (BAT) using flow cytometry (FC) got demonstrated through the expression of CD63 molecules that basophils of atopics donors can be activated when stimulated by serum of patients with CU (supposedly autoimmune). This paper aims to analyze the autologous serum skin test (ASST) in relation to the BAT as well as evaluating the IL3 receptor (CD123) and nonspecific autoantibodies IgG bound to basophils of patients with chronic urticaria. METHODS: We studied 33 adults (24 women) with CU with a mean age of 42.5 + 14 years, of which 22 with ASST positive and 11 with ASST negative. It was done through the analysis by FC of CD63 molecules expression on basophils from an atopic donor after stimulation by serum of these patients. We used as control the serum from 4 volunteers (without urticaria). Also we researched the CD123 molecule expression and IgG nonspecific autoantibodies in basophils from patients with CU. RESULTS: We found 21 (63.6%) patients with positive BAT, of these 14 (66.6%) were ASST positive and 7 (33.3%) were ASST negative. Taking as parameter the BAT, we found an accuracy of 54.5% for the ASST, a sensitivity of 66%, specificity 33%, positive predictive value of 63% and negative predictive value of 36%. Comparing the expression intensity (mean with SD) of IgG autoantibodies in patients' basophils with positive and negative ASST there was not statistical difference (for a P < 0.05); the same was true when comparing the autoantibodies (IgG) between groups with BAT positive and with BAT negative. We also didn't find statistical difference (for a P < 0.05) of receptor expression of IL3 (CD123) between the groups. CONCLUSIONS: Taking as parameter the BAT for diagnosis of autoimmune CU this study found that ASST is accurate about 55%. There was no statistical difference when comparing the expression of IgG nonspecific autoantibodies and CD123 molecule, between groups.