아주대학교

초록/요약

Objectives: Egg allergy is one of the most common food allergies in children. Specific IgE antibodies to egg white is associated with the outcome of oral challenge tests, and specific IgE antibodies to ovomucoid have been suggested as prognostic factors of clinical tolerance to heated egg in children with egg allergy. The aim of this study was to firstly to assess the diagnostic value and optimal cutoff levels of baseline specific IgE antibodies to egg white, ovalbumin, and ovomucoid in predicting anaphylaxis, and secondly to evaluate the clinical usefulness of the specific IgE antibodies in predicting persistence of immediate-type allergic reactions in young children. Methods: This study included 49 children younger than 24 months of age who visited the Pediatric Allergy Clinic of Ajou University Hospital from January 2008 to September 2013 and had undergone measurements of specific IgE antibodies to egg white by means of ImmunoCAP at least twice. Group A was composed of 10 children who had a history of anaphylaxis after ingestion of heated egg. Group B was composed of 18 children who had experienced non-anaphylactic allergic reactions after ingestion of heated egg. Group C was the not-exposed-sensitization group. Baseline concentrations of total IgE as well as specific IgE antibodies to egg white, ovalbumin, and ovomucoid were quantified and compared between groups. For subjects in group A and B, follow-up measurements of specific IgE antibodies to ovalbumin and ovomucoid were done. Results: The mean age of subjects was 9.4 months. There were no significant differences in the mean ages, gender, feeding history, sensitization to other food allergens and family history of allergic diseases between groups. The percentages of diagnosed atopic dermatitis, allergic rhinitis and allergic conjunctivitis did not show significant differences between groups, but the percentage of diagnosed asthma was significantly higher in group A than group B (p<0.001) or group C (p=0.002). Children with a history of anaphylaxis after ingestion of heated egg had considerably higher baseline levels of specific IgE antibodies to egg white (p<0.001)as well as significantly higher levels of specific IgE antibodies to ovalbumin (p=0.008) than children who had non-anaphylactic allergic reactions to heated egg. The baseline level of specific IgE antibodies to ovomucoid was higher in group A (mean±SD 31.2±36.8 kU/L) than group B (7.8±15.0 kU/L) but the difference was not statistically significant (p=0.08). On follow-up assessment after the mean interval of 22 months, all 18 subjects in group B had outgrown their egg allergy and had significantly lower levels of specific IgE to egg white (p=0.001) and ovalbumin (p=0.003) than the baseline levels. The follow-up concentration of specific IgE antibodies to ovomucoid was not significantly lower than the baseline concentration (p=0.199). Receiver operating characteristic analysis showed that specific IgE antibodies to egg white were more useful than specific IgE antibodies to ovalbumin or ovomucoid for the diagnosis of anaphylaxis in young children with egg allergy. The optimal cutoff point 78.9 kUA/L for specific IgE antibodies to egg white resulted in a clinical sensitivity of 80% and a specificity of 94%. Conclusion: Baseline concentration of specific IgE antibodies to egg white was a more useful marker than specific IgE antibodies to ovalbumin or ovomucoid, in predicting anaphylaxis in young children with egg allergy. Comparison between baseline and follow-up concentrations of specific IgE antibodies to egg white and ovalbumin was useful in predicting persistence of immediate-type allergic reactions to heated egg.