Detection of Ovomucoid-Specific Low-Affinity IgE in 14-Month-Old Infants and Its Relationship with Eczema

Abstract

Norio Kawamoto, MD, PhD, Norio Kamemura, PhD, Hiroshi Kido, MD, PhD, Toshiyuki Fukao, MD, PhD; Gifu University, Gifu City, Japan, The University of Tokushima, Japan. RATIONALE: We previously demonstrated the presence of low-affinity IgE in human cord blood by using a newly developed high-sensitivity method. In this study, we investigated the presence of low-affinity IgE detected in their early life and observed its relationship with the eczema. METHODS: We conducted a birth cohort study (n5110) with collecting sera at birth (CB), 6 months (6M) and 14 months (14M) of age. We monitored ovomucoid (OM) and egg white (EW) specific-IgE (sIgE) on UniCAP and a glass slide (GCP)-chip. Affinity characteristics of OM-sIgE at 14M were analyzed in the presence or absence of a mild chaotropic agent, diethyl amine (DEA). RESULTS: Among 45 participants with positive for OM-sIgE on GCPchip at 14M, 23 participants showed negative and 22 showed positive for OM-sIgE by UniCAP at same age. We next compared two representative groups in positive by GCP-chip at 14M; a group with OMand EW-sIgE levels of 0.34 Ua/mL (n510). Sera of the former group showed a larger shift of binding inhibition curves after addedDEA (40mM) than that of matched, indicating the existence of low-affinity IgE. We were categorized by the diagnosis of eczema at 6M and 14M. No-eczema group had higher percentages of having low-affinity IgE as well as lower percentages of high-affinity IgE. CONCLUSIONS: We newly detected allergen-specific low-affinity IgE even in the human peripheral blood at 14M and eczema may risk factor for developing high-affinity IgE, not low-affinity IgE.