Performance evaluation of a laboratory-developed light-initiated chemiluminescence assay for quantification of egg white-specific IgE.

BACKGROUND: Specific IgE (sIgE) testing has become one of the most important tools for diagnosing IgE-mediated food allergy. Enzyme-linked immunosorbent assay (ELISA) and dot-enzyme-linked immunosorbent assay (Dot-ELISA) have been used to measure sIgE in clinical widely. Light-initiated chemiluminescence assay (LICA) is a new method for measuring allergen-sIgE. We aimed to establish a LICA method for quantitative detection of egg white-sIgE and evaluate its performances. METHODS: The best chemibeads coupling method in detecting egg white-sIgE was selected, and a LICA method for quantitative detection of egg white-sIgE was established. The precision study was performed according to Clinical and Laboratory Standards Institute (CLSI) EP5-A2. Detection capability which contains limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) was evaluated according to National Health Commission of the People's Republic of China (NHC) WS/T 514-2017. Linear range was evaluated according to CLSI EP6-A. All data were analyzed using SPSS software. RESULTS: Precision contains repeatability and intermediate precision. The CV of repeatability ranged from 2.72% to 7.29%, and the CV of intermediate precision ranged from 4.93% to 8.64%. The LoB, LoD, and LoQ of the assay were 0.000 kUA/L, 0.053 kUA/L, and 0.076 kUA/L. The assay linear range was 0.076-34.125 kUA /L (r = 0.9979 ≥ 0.9900). CONCLUSION: This laboratory-developed LICA method can detect egg white-sIgE, and performance meets clinical requirements. This method shows rapid turnaround cycles and high sensitivity. It can be used as an alternative method for clinical detection of egg white-sIgE.

Diagnostic values for egg white specific IgE levels with the skin prick test in Turkish children with egg white allergy.

BACKGROUND: The diagnostic values for the skin prick test (SPT) diameters and egg white-specific IgE (EW-sIgE) levels that will allow us to predict the result of the oral food challenge test (OFC) in the diagnosis of egg white allergy vary by the community where the study is carried out. OBJECTIVE: This study aimed to determine the diagnostic values of SPT and EW-sIgE levels in the diagnosis of egg white allergy. METHODS: 59 patients followed with the diagnosis of egg allergy September 2013 to September 2015 were included in our retrospective cross-sectional study. The patients were investigated in terms of egg and anaphylaxis history or the requirement of the OFC positivity. The demographic, clinical and laboratory findings of the cases were recorded, and they were compared with the patients with the suspected egg allergy but negative OFC (n=47). RESULTS: In the study, for all age groups, the value of 5mm in SPT was found to be significant at 96.4% positive predictive value (PPV) and 97.8% specificity and the value of 5.27kU/L for EW-sIgE was found to be significant at 76% PPV and 86.6% specificity for egg white. The diagnostic power of the SPT for egg white (AUC: 72.2%) was determined to be significantly higher compared to the diagnostic power of the EW-sIgE (AUC: 52.3%) (p<0.05). CONCLUSION: Along with the determination of the diagnostic values of communities, the rapid and accurate diagnosis of the children with a food allergy will be ensured, and the patient follow-up will be made easier.

Laboratorial characteristics of patients with diarrhoea suffering from egg white allergy.

BACKGROUND: Egg allergy is associated with diarrhoeal symptoms. However, the mechanism underlying allergic diarrhoea remains unclear. OBJECTIVE: To determine whether egg white-specific IgE antibodies coexist with egg white-specific IgG antibodies in patients with egg allergy featuring diarrhoeal symptoms, and whether there is any relationship between these two antibody types. METHODS: A total of 89 patients with egg allergy featuring diarrhoeal symptoms (average age, 23.2 years; range, 1-78 years), all of whom tested positive for egg white-specific IgG, were enrolled in this study. The concentration of total IgE, egg white-specific IgE and number of eosinophils in the serum were determined. RESULTS: Among the 89 egg white allergic patients tested, 49 (55.1%) patients showed high reactivity to egg white-specific IgG, 48 (53.9%) patients had elevated serum total IgE levels, and 25 (28.1%) patients had elevated absolute eosinophil numbers. Out of the 89 egg white allergic patients, 25 showed elevated egg white-specific IgE antibody levels. Of the 25 patients who were positive for egg white-specific IgE antibody, 21 presented high sensitive reaction to egg white-specific IgG, three presented moderate sensitive reaction to egg white-specific IgG, and one presented mild sensitive reaction to egg white-specific IgG. A moderate correlation between egg white-specific IgG and egg white-specific IgE, egg white-specific IgG and absolute eosinophil number was found in the egg white allergic patients (r=0.438, P=0.000; r=0.322, P=0.002). Egg white-specific IgE levels varied in different age groups; the egg white-specific IgE concentration of younger patients (age≤18 years, mean rank 54.29) was significantly higher than that of the adult patients (age>18 years, mean rank 34.61) (Z=-3.629, P=0.000). CONCLUSION: Egg white-specific IgE antibody could coexist with egg white-specific IgG antibody in patients suffering from egg white allergy. Aberrant changes in the concentration of egg white-specific IgE antibody were associated with the presence of egg white-specific IgG antibody.