Basophils Autoinduced Degranulation (BAD) Test. A New Variant Of Basophils Activation Test (BAT) As Reliable In Vitro Tool For The Diagnosis Of Chronic Autoimmune Urticaria (CAU)

Rationale It is well known that 15-30% of chronic idiopathic urticaria (CIU) have autoimmune aetiology. The diagnosis of CAU is based on the demonstration of the presence of anti-FcεRIα and/or anti-IgE autoantibodies in the serum. The commonly screening procedures is represented by Basophil Histamine Release test (BHR) and Autologous Serum Skin Test (ASST) associated, due to their low sensitivity and specificity (70%-80%). The aim of this study is to develop a new method more reliable and faster to diagnose CAU. Methods 100 CIU patients were recruited. Serum and peripheral whole blood were collected. The serum was divided into two parts, one of which was decomplemented (DS), and the other was used whole (WS). These sera were used to stimulate autologous blood cells in order to perform the BAD test by flow cytometry. Our method uses a two-colours approach with anti-human CCR3 and CD63, subsequent to the stimulation of basophils with DS and WS. Results 24 of 100 CIU patients showed a significant increase of CD63 on basophils stimulated with whole and/or decomplemented serum. Of these 12 patients showed degranulation only when stimulated with whole serum, 1 with decomplemented serum and 11 with both stimuli. Conclusions BAD test is useful for the quantitative determination of the basophils degranulation. Recent studies conducted with similar methods confirmed that the sensitivity and specificity of BAD test are approximately of 95% and 90%. Our method is more reliable, faster and cheaper than previous that used leucocytes separation or three-colours procedures. Also the sensitivity of BADt could be enhanced associating the activation marker CD203c.