Immunological activity of recombinant Ole e 1 in patients with Olea europaea pollinosis

Abstract

Background: Recombinant allergens have potential advantages over conventional allergenic extracts. However, these recombinant allergens should be evaluated for their antigenic activity and compared with their natural counterparts before being used for clinical purposes.

Methods: We studied 33 patients with seasonal rhinitis and/or bronchial asthma and a positive skin prick test to Olea europaea pollen extract, 10 atopic patients with no history of pollinosis and a negative skin prick test to O. europaea extract and 10 healthy controls. Skin prick tests and determination by ELISA of specific IgE to natural Ole e 1 (nOle e 1) and recombinant Ole e 1 (rOle e 1) expressed in Pichia pastoris were performed in all patients and controls. Inhibition assays were performed between nOle e 1 and rOle e 1 by ELISA.

Results: All patients with O. europaea pollinosis had positive skin test responses to both commercial O. europaea extract and nOle e 1 allergen, and all reacted to rOle e 1 on the skin prick test. The nonatopic and atopic control subjects with negative olive pollen skin test results did not react to rOle e 1 on the skin prick test, even at the highest concentrations, confirming the specificity of this test. We found a weak correlation between the wheal surface area produced by the prick test with nOle e 1 and the wheal surface area produced by rOle e 1 at 10 microgram/ml (r = 0.42, p < 0.05). Comparison of specific IgE against both nOle e 1 and rOle e 1 in the patients did not reveal any significant difference. There was a strong correlation between the amount of specific IgE against nOle e 1 and rOle e 1 (r = 0.99, p < 0.01). The two proteins displayed the same extent of binding inhibition to IgE antibodies in ELISA inhibition experiments.

Conclusions: These results confirm the immunological activity of rOle e 1 expressed in P. pastoris and indicate that Ole e 1 is one of the major allergens in O. europaea pollinosis as evaluated by skin prick test and serological methods. The correlation between rOle e 1 and nOle e 1 in skin test results and serologic data indicates the potential of recombinant allergens for clinical applications and diagnosis of O. europaea pollen allergy.