Diagnosis of food allergy to fruits by modified prick-prick testing and oral-pharyngeal provocative test

Dziarkach A.F., Aliakhnovich N.S.

Vitebsk State Medical University, Vitebsk

Aim. Evaluation of the diagnostic significance of modified prick-prick testing and oral-pharyngeal provocative test (OPPT) in detecting food allergy (FA) to apple/tangerine in patients with seasonal allergic rhinitis, conjunctivitis and sensitization to pollen allergens.
Materials and methods. 66 patients with allergic rhinitis, conjunctivitis and sensitization to pollen allergens were examined. 40 patients noted symptoms of allergy to apple (study group № 1), 26 – to citrus fruits (including tangerine) (study group № 2). To confirm FA, study group № 1 underwent a prick-prick test with various apples and OPPT with apple juice solution with assessment of tryptase, peroxidase activity, K+, NH4+ and Ca2+ cations in the oral fluid (OF) before and 40 minutes after the provocation; study group №2 – an intradermal test with a water-salt extract of the tangerine allergen or a prick-prick test with native tangerine and OPPT with water-salt extract of the tangerine allergen solution or solution tangerine juice with the determination of peroxidase activity of the oral fluid (PAOF) before and after 40 minutes after provocation. A description of 2 clinical cases of patients with seasonal allergic rhinitis, conjunctivitis and sensitization to pollen allergens with allergic reactions to plant products is presented.
Results. The prick-prick test with native apple was positive in 95 % of the examined patients with seasonal allergic rhinitis, conjunctivitis and sensitization to pollen allergens, with tangerine – in 44 % of patients, intradermal test with water-salt extract of tangerine allergen – only in 12 % of patients. In the study group № 1 after OPPT with apple juice solution, an increase in tryptase in OF was observed in 70 % of patients (by 16 % or more compared to the initial one, p < 0.05). In 74 % of patients of the study group № 1, an increase in PAOF was registered after provocation with apple juice solution (by 19 % or more compared with the initial level, p < 0.05). 81 % of patients with allergic reactions to apple showed an increase in the concentration of K+ cations in the OF (by 17 % or more, p < 0.05), of which 50 % showed a parallel decrease in NH4+ cations after OPPT with apple juice solution, p < 0.05. OPPT with solutions of water-salt extract of tangerine allergen and tangerine juice with an increase in PAOF was positive in 53 % and 44 % of patients in the study group № 2, respectively (the increase was 22 % or more, p < 0.05).
Findings. The modified prick-prick test with native foods allows for the diagnosis of FA to fruit in patients with seasonal allergic rhinitis, conjunctivitis and pollen allergen sensitization with a sensitivity of 95 %, a specificity of 100 % (apple), 44 % and 100 % (tangerine), respectively. A high diagnostic significance of OPPT with apple juice solution was found, followed by an assessment of tryptase in OF (sensitivity – 70 %, specificity – 100 %), PAOF (sensitivity – 74 %, specificity – 87 %) of K+ cations (sensitivity – 81 %, specificity – 100 %) in the detection of FA to fruits. OPPT with a solution of water-salt extract of the tangerine allergen and tangerine juice with an assessment of PAOF showed sensitivity of 53 % and 44 %, specificity – 88 % and 89 %, respectively.