Serum eosinophil-derived neurotoxin: a new promising biomarker for cow's milk allergy diagnosis

Background: Cow's Milk Allergy (CMA) diagnosis is often a challenge due to the non-specific nature of symptoms and lack of a confirmatory diagnostic test. To our knowledge no previous studies investigated serum Eosinophil-Derived Neurotoxin (sEDN) in CMA. So, we aimed to assess the role of sEDN in CMA diagnosis. Methods: Forty-five infants with CMA were compared to 45 infants with functional gastrointestinal disorders (FGIDs) and 45 healthy controls. For all participants, Cow's Milk-related Symptom Score (CoMiSS) was documented, and sEDN level with hematological parameters were measured before starting elimination diet. Results: Receiver operation characteristic (ROC) curve identified sEDN > 14 ng/mL and CoMiSS > 9 as the optimal cut-off points to discriminate CMA from other groups with sensitivity 86.67%, 97.78% and specificity 60.00%, 78.89% respectively. Additionally, absolute neutrophil count (ANC) showed the highest sensitivity and specificity (80.0% and 78.89%) among hematological parameters. Although CoMiSS and ANC showed a significant positive correlation with sEDN in CMA group, CoMiSS was the only significant predictor for sEDN in multivariate linear regression. Conclusions: sEDN showed high sensitivity in discriminating infants with and without CMA. Therefore, it is suggested as a potential biomarker for CMA diagnosis. Also, ANC should be closely monitored in these infants. Impact: center dot CMA presents with high heterogeneity, which complicates the diagnosis especially non-IgE-mediated and mixed types. So, oral food challenge continues to be the gold standard for its diagnosis. center dot ROC curve identified CoMiSS > 9 as the best cut-off point to identify CMA. However, CoMiSS is a good awareness tool for CMA but not a diagnostic tool. center dot sEDN level was significantly higher in infants with CMA with a good diagnostic performance in differentiating them than those without CMA. So, it is suggested as a potential biomarker for CMA diagnosis. center dot ANC could have a role in CMA diagnosis and differentiating it from FGIDs.