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Keywords:

  • circular dichroism;
  • diagnosis;
  • IgE binding;
  • Par j 1;
  • Par j 2;
  • Parietaria judaica;
  • recombinant allergen;
  • skin prick test

Summary

Background Parietaria judaica pollen is one of the main causes of allergic diseases in the Mediterranean area and contains two major allergens, called Par j 1 and Par j 2.

Objective To evaluate the diagnostic potential of natural and recombinant forms of Par j 1 and Par j 2 in comparison with standardized P. judaica pollen extract.

Methods Thirty patients allergic to P. judaica pollen and 15 control patients were investigated. Skin prick tests and determination of specific IgE levels were performed with commercial P. judaica extract, natural Par j 1 and Par j 2, and recombinant forms of both allergens expressed in P. pastoris.

Results The whole group of patients with allergy to P. judaica had a positive skin test reaction to purified nPar j 1–Par j 2 and rPar j 2 at 5 μg/mL, and no false-positive reactions were detected. Natural and recombinant Par j 1 and Par j 2 showed no significantly different responses in skin tests compared with P. judaica extract. A high correlation was found between the serum-specific IgE levels to P. judaica extract vs. natural (R=0.996; P<0.001) and recombinant allergens (R=0.887 and 0.982 for rPar j 1 and rPar j 2, respectively; P<0.001). rPar j 2 displayed a 100% sensitivity and specificity among P. judaica-allergic patients.

Conclusions In vivo and in vitro diagnosis of P. judaica pollen allergy could be simplified using rPar j 2. This protein showed comparable IgE response and skin prick reactivity with those produced by P. judaica pollen extract.