IgE and IgG4 binding to lentil epitopes in children with red and green lentil allergy.

BACKGROUND: The consumption of lentil is common in the Mediterranean area and is one of the causes of IgE-mediated food allergy in many countries. Len c 1 is a well-defined allergen of lentil and approximately 80% of the patients with lentil allergy recognize the purified Len c 1 protein. We sought to identify IgE and IgG4 sequential epitopes of Len c 1 in patients with red and/or green lentil allergy. We also aimed to determine IgE and IgG4 binding differences between those patients who had outgrown or remained reactive to lentil. METHODS: Children with IgE-mediated lentil allergy were included in the study. We applied a microarray immunoassay to determine the characterization of positive IgE and IgG4 binding to Len c 1 epitopes in the patients' sera. RESULTS: The peptides specifically recognized by IgE and IgG4 antibodies were mainly detected between peptides 107 and 135 of Len c 1. The signal intensities of positive epitopes were significantly greater in reactive patients than tolerant ones (P = .008 for IgE and P = .002 for IgG4). Moreover, IgE and IgG4 antibodies bound largely the same sequential epitopes in patients who remained reactive or outgrew their allergy. CONCLUSION: IgG4-binding epitopes in lentil allergy were identified and IgE and IgG4 binding to epitopes in both red and green lentils was compared. Our data regarding signal intensity differences between reactive and outgrown patients and overlap binding of IgE and IgG4 antibodies may be important for the development of more accurate diagnostic tests and understanding of natural tolerance development.

A new Luminex-based peptide assay to identify reactivity to baked, fermented, and whole milk.

BACKGROUND: The majority of children with cow's milk allergy (CMA) tolerate baked milk. However, reactivity to fermented milk products such as yogurt/cheese has not been previously evaluated. We sought to determine whether children with CMA could tolerate yogurt/cheese and whether a patient's IgE and IgG4-binding pattern to milk protein epitopes could distinguish clinical reactivity. METHODS: Four groups of reactivity were identified by Oral food challenge: baked milk reactive, fermented milk reactive, whole milk reactive, and outgrown. sIgE and sIgG4 binding to milk protein epitopes were assessed with a novel Luminex-based peptide assay (LPA). Using machine learning techniques, a model was developed to predict different degrees of CMA. RESULTS: The baked milk reactive patients demonstrated the highest degree of IgE epitope binding, which was followed sequentially by fermented milk reactive, whole milk reactive, and outgrown. Data were randomly divided into two groups with 75% of the data utilized for model development (n = 68) and 25% for testing (n = 21). All 68 children used for training were correctly classified with models using IgE and IgG4 epitopes. The average cross-validation accuracy was much higher for models using IgE plus IgG4 epitopes by LPA (84.8%), twice the performance of the serum component proteins assayed by UniCAP (41.9%). The performance of the model on "unseen data" was tested using the 21 withheld patients, and the accuracy of IgE was 86% (AUC = 0.89) while of IgE+IgG4 model was 81% (AUC = 0.94). CONCLUSION: Using a novel high-throughput LPA, we were able to distinguish the diversity of IgE/IgG4 binding to epitopes in the varying CMA phenotypes. LPA is a promising tool to predict correctly different degrees of CMA.

Role of specific IgE in predicting the clinical course of lentil allergy in children.

BACKGROUND: Legumes, and particularly lentils, are frequently consumed in Mediterranean, Middle Eastern, and some Asian countries. The aim of this study was to document the demographic features of children with lentil allergy and to determine the role of specific IgE (sIgE) in predicting the risk of clinical reactivity and disease persistence. METHODS: Thirty children were enrolled. The diagnosis of lentil allergy was based on convincing history of symptoms or anaphylaxis after the ingestion of lentils, with positive skin tests and/or sIgE to lentils. To determine the diagnosis and prognosis of lentil allergy, 24 children were evaluated with food challenges. RESULTS: The median age at the onset of symptoms was 1.5 yr (0.9-2.3) (inter-quartile range). The most frequent symptoms were immediate cutaneous (97%) and respiratory (30%) reactions, whereas eight patients (27%) reported anaphylactic reactions. The median level of lentil sIgE at the time of diagnosis was 3 kU/l (1.2-9.6). Of the 24 challenges, 12 were positive. Fifteen patients (50%) outgrew the lentil allergy by the age of 3.5 (2.5-11) years. Children with an initial lentil sIgE < 4.9 kU/l had a significantly higher likelihood (68.4% vs. 18.2%) of outgrowing the lentil allergy than children with an initial lentil sIgE ≥ 4.9 k/l (p = 0.008). CONCLUSIONS: Our results suggest that sIgE levels may be important for predicting clinical reactivity and persistence of lentil allergy.