3.2. Comparison of IgD and IgG4 serum levels in the egg allergic and NEA groups.
The CAE group exhibited lower serum levels of EW-specific IgD compared to the NEA group and lower serum levels of OVA-specific IgD compared to the PAE group (Fig. 1B and 1G). In addition, the CAE group had the lowest OVM-specific IgD serum levels among all of the groups (Fig. 1E). It has been reported that the natural development of tolerance by continuous ingestion of heated egg in egg-allergic patients is associated with an increase in EW-, OVM- and OVA-specific IgG4 levels.8-10 Consistent with these findings, we observed the lowest serum levels of EW-, OVA-, and OVM-specific IgG4 in the CAE group, followed by the PAE and OGE groups (Fig. 1C, F, and H).
OVM-specific IgD significantly correlated with OVM-specific IgG4 in all groups except the CAE group (Spearman’s rank correlation coefficient; ρ = 0.10, 0.78, 0.71, and 0.70 in CAE, PAE, OGE, and NEG groups, respectively). Furthermore, we observed a significant correlation between EW-specific IgD and IgG4 in the PAE group (ρ = 0.84). These findings suggest that serum levels of OVM-specific IgD, but not EW-specific IgD, are associated with outgrowing egg allergy.