Exploring the role of basophil activation test in diagnosis of Dermatophagoides farinae sensitization and evaluation of therapeutic efficacy of subcutaneous immunotherapy in children.

It aims to detect basophil activation ratio (%CD63+ ) in peripheral blood of children with allergic asthma and rhinitis by using flow cytometry (FCM), so as to analyse the application values and clinical relevance of the basophil activation test (BAT) in diagnosis of Dermatophagoides farinae (Derf) sensitization and monitoring therapeutic efficacy of subcutaneous immunotherapy (SCIT). It was a prospective study. From the newly diagnosed children with asthma and rhinitis in our paediatric clinic, 39 patients diagnosed Derf sensitization and 15 patients not allergic to Derf were enrolled; another 4 healthy children were taken as control group. Using Derf extracts in concentration of 1, 10 μg/mL and 100 μg/mL as the stimulus, BAT results were expressed as %CD63+ in diagnosis of Derf sensitization and its correlation with skin prick tests (SPT), serum total IgE (tIgE), specific IgE (sIgE), sIgE/tIgE, specific IgG4 (sIgG4), FEV1%pred in pulmonary ventilation function, exhaled nitric oxide (FeNO), children asthma control test (C-ACT) and visual analogue scale (VAS) were observed. In sensitization group, %CD63+ , sIgG4 and clinical indicators were detected again from patients who had received SCIT to analyse their internal connections. The average levels of %CD63+ in 3 concentrations showed an increasing concentration-dependent trend overall. %CD63+ in sensitization group was significantly higher than that in the other 2 groups. The analysis of ROC for Derf sensitization showed the area under the curve (AUC) for BAT in 3 concentrations was higher than that for sIgE whose AUC is 0.893. %CD63+ was positively correlated with SPT grade, sIgE, sIgE/tIgE and VAS, and negatively correlated with C-ACT. In patients receiving SCIT, %CD63+ became lower and sIgG4 level became higher than pretreatment. There was no obvious change in sIgG4 in those who had not received SCIT. BAT is a reliable and non-invasive tool for diagnosis of Derf sensitization in children with asthma and rhinitis. CD63-based BAT has clinical value to monitor outcome of SCIT, and the change in basophil activation is inherently related to induction of sIgG4.