Influence of high-pressure treatment on allergenicity of rDau c1 and carrot juice demonstrated by in vitro and in vivo tests

The aim of our study was to detect the influence of high-pressure treatment (HPT) on the allergenicity of recombinant allergen rDau c1 and carrot juice using in vitro and in vivo tests. The buffer solution of recombinant main carrot allergen rDau c1 for the basophil activation test (BAT) and Western blot (WB) was used. Dau c1 was pre-treated by pressure 500 MPa for 10 min and different temperatures (30 °C, 40 °C, 50 °C) and pressure from 400 to 550 MPa for 3 and 10 min. Neither the HPT from 400 to 550 MPa for 3 and 10 min nor the HPT at 500 MPa for 10 min and temperatures 30 °C, 40 °C, and 50 °C had the influence on basophil activation by rDau c1. Serum samples of birch pollen allergic patients reacted in WB with solution of rDau c1 treated by HP 500 MPa for 10 min at temperature 30 °C, 40 °C, and 50 °C. This pressure procedure did not influence the immune reactivity of rDau c1 in WB test. The structural changes of rDau c1 caused by HPT studied by circular dichroismus spectra were found. Mild increase of the beta-sheet structure was observed. The main changes were seen in rDau c1 samples treated 10 min at 500 MPa and temperature 50 °C. The influence of HPT on the allergenicity of carrot juice was studied afterward. The reactivity in skin prick tests and BAT did not show any influence of HPT on allergenicity of carrot juice. Pressure of 500 MPa for 10 min and temperature 30 °C, 40 °C, and 50 °C did not inactivate allergen Dau c1 in carrot juice in WB. HPT from 450 to 550 MPa for 3 and 10 min at temperature 30 °C had no influence on the immune reactivity of Dau c1 in carrot juice. Nineteen patients underwent the double-blind, placebo-controlled food challenge. Thirteen of them reacted to placebo and were excluded, one patient did not react at any material (placebo, HPT material and fresh frozen carrot juice), three patients had positive test (reacted on HPT material and non-treated fresh frozen carrot juice), and two patients had negative reaction (reacted only on fresh frozen material). We could not confirm the influence of HPT on allergenicity of rDau c1 and carrot juice using in vitro and in vivo tests.