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Diagnosis of cypress pollen allergy: in vivo and in vitro standardization of a Juniperus ashei pollen extract

Authors


Maud Hrabina
Research Department
Stallergènes SA 6, rue Alexis de Tocqueville
92183 Antony Cedex
France

Abstract

Background: Cypress pollen allergy is a major cause of rhinoconjunctivitis and asthma in the Mediterranean area. The nonstandardized cypress allergen extracts currently available for the diagnosis of cypress allergy have a low level of activity. The search for an active material has led to the selection of Juniperus ashei (Ja) pollen because of its very high cross-reactivity with cypress extracts and its superior allergenic activity. The aim of this study was to characterize in vitro and calibrate in vivo an in-house reference extract (IHRS) of J. ashei pollen and determine the specificity and sensitivity of a standardized Ja extract for the prick test diagnosis of cypress allergy.

Methods:Juniperus ashei pollen extract was analysed by 2-D electrophoresis. The IHRS Ja extract was calibrated by skin prick testing in 28 cypress-allergic patients. The sensitivity and specificity of cypress allergy diagnosis using a standardized Ja extract was studied by skin prick test in 42 cypress-allergic patients and 53 nonallergic patients. Jun a 1 content of the IHRS was determined by a monoclonal antibody-based electrophoretic technique.

Results: The Jun a 1 content of the 100 IR/ml Ja IHRS extract was 180 μg/ml. For in vivo diagnosis of cypress allergy, Ja pollen extract demonstrated a sensitivity of 95%, a specificity of 100%, a negative predictive value of 96%, and a positive predictive value of 100%.

Conclusion: Standardized Ja pollen extract is therefore a very appropriate tool for the in vivo diagnosis of cypress pollen allergy and good candidate for specific immunotherapy.

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