Association of serum eosinophilia and total immunoglobulin E concentration with the risk of allergic symptoms and allergic sensitization, respectively: A 2-year follow-up study

ObjectivesSerum eosinophil percentage (SEP), eosinophil cationic protein (ECP) concentration, and total IgE (TIgE) concentration are known to increase in patients with allergic disease; however, the relevance of these elevated markers in children with negative allergic test results remains unclear. Therefore, this 2-year follow-up study aimed to investigate whether SEP, ECP concentration, and TIgE concentration are associated with an increased risk for allergic sensitization and allergic symptoms.MethodsIn 2012, SEP, ECP concentration, and TIgE concentration of third- and fourth-grade students from 6 elementary schools were measured. Skin prick test was performed, and the presence of allergic nasal symptoms was investigated using a questionnaire. In 2014, the same examinations were performed in the same set of students, who were then in the fifth and sixth grades, respectively, of the same schools. The cut-off value and usefulness of serologic markers (eosinophil count, ECP concentration, and TIgE concentration) were calculated using the receiver operating characteristic curve.ResultsSerum eosinophil percentage (cut-off value, 3.8%) was associated with the newly developed allergic nasal symptoms (sensitivity, 77.9; specificity, 41.8). A high serum TIgE concentration (cut-off value, 17.7 IU/mL) was also associated with the risk for allergic sensitization (sensitivity, 46.3; specificity, 85.3).ConclusionSEP and TIgE concentration were associated with the development of allergic symptoms and allergic sensitization, respectively, 2 years after the first examination.