Increased ratio of pollock roe-specific IgE to salmon roe-specific IgE levels is associated with a positive reaction to cooked pollock roe oral food challenge.

BACKGROUND: Anaphylaxis and immediate-type fish roe allergies have been reported worldwide, and, in Japan, fish roe is the sixth most common food allergen. No oral food challenges (OFCs) have used pollock roe (PR), which is reported to have high cross-reactivity with salmon roe (SR). Therefore, we administered an OFC using cooked PR to evaluate PR- and SR-specific immunoglobulin E (IgE) levels and allergic reactions in patients with PR sensitivity.

METHODS: This retrospective study evaluating patient characteristics and responses to OFCs was conducted with 10-20 g of cooked PR, between April 2006 and November 2016.

RESULTS: We assessed 51 patients (median age: 6.8 years). All had PR sensitization, 6 (12%) with a history of immediate reactions to PR, and 18 (35%) of immediate reactions to SR. Median PR-specific and SR-specific IgE values were 3.4 kUA/L and 9.9 kUA/L, respectively. Seven patients (14%) had a positive OFC. There was no anaphylaxis. Induced symptoms were mild and included localized urticaria, throat pruritus, intermittent cough, and mild abdominal pain. We treated one patient with mild abdominal pain with oral antihistamines. There were no significant differences in history of immediate reaction to PR and PR-specific IgE titers between OFC-positive and OFC-negative patients, although significant differences were found for PR-specific IgE titers adjusted for SR-specific IgE (p = 0.025) and PR-specific IgE/SR-specific IgE ratio (p = 0.009).

CONCLUSIONS: Increased PR-specific IgE/SR-specific IgE ratio or PR-specific IgE levels adjusted for SR-specific IgE levels were risk factors for OFC positivity.