BACKGROUND:

In a previously reported CoFAR study, 55 subjects with egg allergy underwent randomized, placebo-controlled egg oral immunotherapy (eOIT). Active treatment induced desensitization in most and sustained unresponsiveness (SU) in a smaller subset. We hypothesized that component-resolved analysis of IgE, IgG4, IgA, IgA1, and IgA2 may identify potential biomarkers of SU in OIT subjects.

METHODS:

Longitudinal samples for 51 egg-allergic subjects (37 active, 14 placebo) were available. Egg white- (EW), ovalbumin- (OVA), and ovomucoid (OVM)-specific levels of IgA, IgA1, and IgA2 were quantified by ELISA. IgE and IgG4 to these antigens were quantified using ImmunoCAP^® . Clinical responders achieved SU to egg; all others were considered non-responders. Between-group comparisons were made amongst active and placebo, as well as responders and non-responders.

RESULTS:

No placebo subjects achieved responder status. Through month 48, among the 37 active subjects, baseline IgE-OVM was lower in responders (median 3.97 kU/L, n=19) than non-responders (10.9 kU/L, n=18, p=0.010). Logistic regression analysis revealed lower baseline IgE-EW (p = 0.038), IgE-OVM (p = 0.032) and a higher IgG4:IgE-OVM ratio (p=0.013) were associated with clinical response. Relative increases in IgG4-EW, IgA-EW and IgA2-EW were greater in responders (p= 0.024, 0.024, 0.029, respectively). Ratios of IgG4:IgE, IgA:IgE, IgA2:IgE for EW and IgA:IgE for OVA were significantly elevated among responders (p = 0.004, 0.009, 0.028, 0.008, respectively).

CONCLUSIONS:

Increased IgG4-EW, IgA-EW and IgA2-EW during eOIT are associated with clinical response to eOIT. Lower pre-treatment IgE-EW and IgE-OVM are also associated with SU. Future studies are needed to evaluate and validate these potential biomarkers. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.