RationaleThe majority of children with detectable serum specific IgE (sIgE) and/or positive skin prick test (SPT) to peanut do not have peanut allergy. In equivocal cases, oral food challenges (OFC) are required. However, OFC are laborious and not without risk; thus, a test that could accurately diagnose peanut allergy and reduce the need for OFC is desirable.ObjectiveTo assess the performance of basophil activation test (BAT) as a diagnostic marker for peanut allergy.MethodsPeanut allergic (PA,n=44), peanut sensitized but tolerant (PS,n=34) and non-allergic non-sensitized (NA,n=25) children were recruited. Peanut allergy or tolerance was diagnosed by OFC, except in cases of recent anaphylaxis and SPT≥8mm and/or peanut-sIgE≥15KU/L. Patients underwent SPT and sIgE to peanut and to Arah1, Arah2, Arah3, Arah8 and Arah9. Whole blood BAT was performed using flow cytometry.ResultsBAT in PA children showed a peanut dose-dependent up-regulation of CD63 and CD203c whilst there was no significant response to peanut in PS and NA children (p<0.001). ROC curve analysis identified diagnostic cut-offs for BAT, namely 7.3% CD63+ basophils at 100ng/ml of peanut (sensitivity=95%, specificity=96%, positive predictive value=95%, negative predictive value=96%, accuracy=97%). In children with comparable levels of specific IgE to peanut and to Arah1, Arah2 and Arah3 (n=38), BAT had a diagnostic accuracy of 92% as opposed to SPT (82%) and sIgE to peanut (63%) and to Arah2 (76%).ConclusionsBAT proved to be superior to other diagnostic tests in discriminating between peanut allergy and tolerance, particularly in difficult cases with equivocal SPT and sIgE to peanut and its components. RationaleThe majority of children with detectable serum specific IgE (sIgE) and/or positive skin prick test (SPT) to peanut do not have peanut allergy. In equivocal cases, oral food challenges (OFC) are required. However, OFC are laborious and not without risk; thus, a test that could accurately diagnose peanut allergy and reduce the need for OFC is desirable. The majority of children with detectable serum specific IgE (sIgE) and/or positive skin prick test (SPT) to peanut do not have peanut allergy. In equivocal cases, oral food challenges (OFC) are required. However, OFC are laborious and not without risk; thus, a test that could accurately diagnose peanut allergy and reduce the need for OFC is desirable. ObjectiveTo assess the performance of basophil activation test (BAT) as a diagnostic marker for peanut allergy. To assess the performance of basophil activation test (BAT) as a diagnostic marker for peanut allergy. MethodsPeanut allergic (PA,n=44), peanut sensitized but tolerant (PS,n=34) and non-allergic non-sensitized (NA,n=25) children were recruited. Peanut allergy or tolerance was diagnosed by OFC, except in cases of recent anaphylaxis and SPT≥8mm and/or peanut-sIgE≥15KU/L. Patients underwent SPT and sIgE to peanut and to Arah1, Arah2, Arah3, Arah8 and Arah9. Whole blood BAT was performed using flow cytometry. Peanut allergic (PA,n=44), peanut sensitized but tolerant (PS,n=34) and non-allergic non-sensitized (NA,n=25) children were recruited. Peanut allergy or tolerance was diagnosed by OFC, except in cases of recent anaphylaxis and SPT≥8mm and/or peanut-sIgE≥15KU/L. Patients underwent SPT and sIgE to peanut and to Arah1, Arah2, Arah3, Arah8 and Arah9. Whole blood BAT was performed using flow cytometry. ResultsBAT in PA children showed a peanut dose-dependent up-regulation of CD63 and CD203c whilst there was no significant response to peanut in PS and NA children (p<0.001). ROC curve analysis identified diagnostic cut-offs for BAT, namely 7.3% CD63+ basophils at 100ng/ml of peanut (sensitivity=95%, specificity=96%, positive predictive value=95%, negative predictive value=96%, accuracy=97%). In children with comparable levels of specific IgE to peanut and to Arah1, Arah2 and Arah3 (n=38), BAT had a diagnostic accuracy of 92% as opposed to SPT (82%) and sIgE to peanut (63%) and to Arah2 (76%). BAT in PA children showed a peanut dose-dependent up-regulation of CD63 and CD203c whilst there was no significant response to peanut in PS and NA children (p<0.001). ROC curve analysis identified diagnostic cut-offs for BAT, namely 7.3% CD63+ basophils at 100ng/ml of peanut (sensitivity=95%, specificity=96%, positive predictive value=95%, negative predictive value=96%, accuracy=97%). In children with comparable levels of specific IgE to peanut and to Arah1, Arah2 and Arah3 (n=38), BAT had a diagnostic accuracy of 92% as opposed to SPT (82%) and sIgE to peanut (63%) and to Arah2 (76%). ConclusionsBAT proved to be superior to other diagnostic tests in discriminating between peanut allergy and tolerance, particularly in difficult cases with equivocal SPT and sIgE to peanut and its components. BAT proved to be superior to other diagnostic tests in discriminating between peanut allergy and tolerance, particularly in difficult cases with equivocal SPT and sIgE to peanut and its components.