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Contribution of recombinant Parvalbumin Gad c 1 in the diagnosis and prognosis of fish allergy

Carvalho S1, Marcelino J1, Cabral Duarte M1, Costa C1, Barbosa M1, Pereira Dos Santos MC2

1Imunoallergology Department, Centro Hospitalar Universitário Lisboa Norte. Hospital Santa Maria, Lisbon, Portugal
2Clinical Immunology Unit – Instituto de Medicina Molecular, Faculdade de Medicina. Universidade de Lisboa, Lisbon, Portugal

J Investig Allergol Clin Immunol 2020; Vol. 30(5)
doi: 10.18176/jiaci.0437

Background: The prevalence of fish allergy increased in recent years. Gadc1 is a parvalbumin and a major cod allergen, used as a follow-up marker in patients with fish allergy.
Objective: Clinical and laboratory characterizationof a population of patients with fish allergy. Analyze the contribution of thespecific IgE(sIgE) of recombinant parvalbumin Gadc1(rGadc1) and skin prick tests(SPTs) to confirm the acquisition of tolerance to fish.
Methods: Retrospective study of patientswith fish allergy, from July 1st, 2005 to December 31st, 2016. The population was characterized according to demographic data, fish associated with allergic reactions and symptoms. The wheal diameter of the SPT and sIgEfor the fish and rGad c 1 were evaluatedbefore(T0) and after tolerance acquisition(T1).
Results: 81 patients(68% male).Hake(51%), mackerel(30%) and cod(26%) triggered the majority of reactions. The most frequent manifestations were urticaria/angioedema(72%), gastrointestinal symptoms(35%) and eczema(33%);42% of all patients had anaphylaxis. In (T0), the average sIgE values were:cod(32.2kUA/l), sardine(18.4kUA/l), hake(17.5kUA/l), salmon(13.9kUA/l), tuna(4.5kUA/l), and rGadc1(22.9kUA/l). In patients who acquired toleranceto at least one fish species(n=60; 74%), the mean value of rGadc1 in T1(5.1kUA/l) was significantly lower thanT0 (16.8kUA/l)(p=0.001).The values for the average diameter of SPT, evaluations in T0 and T1 for hake(9.42mm/3.79mm) and salmon(7.8mm/2.8mm)were also significant p=0.002 and p=0.026, respectively.
Conclusion: The decrease of sIgE to rGad c 1 and the mean wheal diameter of SPT forhake and salmon can be used as markers of prognosis in the acquisition of tolerance in fish allergy.

Key words: Food allergy, fish allergy, parvalbumin, cross reactivity, recombinant allergen, rGad c 1