Assessment of skin prick test and serum specific IgE detection in the diagnosis of Cupressaceae pollinosis

Background: There is increasing evidence for the relevance of Cupressaceae pollinosis among persons living in geographic areas where theses species are native or imported. Objective: Previously reported problems in obtaining valid allergenic extracts to be used in the diagnosis of this winter pollinosis prompted us to assess the value of available Cupressaceae pollen extracts for in vivo and in vitro diagnosis. Methods: Commercial and in-house allergenic extracts from Cupressaceae and Taxodiaceae families were used for skin prick testing and specific IgE detection in six groups of subjects exposed to a high concentration of Cupressaceae pollen. Results: Four commercial and two in-house Cupressus sempervirens pollen extracts showed low cutaneous reactivity. Positive test results were recorded in 26% of the 713 subjects tested. C. arizonica in-house pollen extracts gave rise to larger cutaneous reactions. Furthermore, the skin prick test response was positive in a greater number of subjects (38%) of the same group. Six commercial immunoassays were able to detect specific IgE to C. sempervirens in rates ranging from 8.1% to 82.1%. Specific IgE to C. arizonica was detected by means of an inhouse immunoenzymatic method in 70.3% of 54 patients with suspected ''cypress'' allergy, and specific IgE to C. sempervirens was detected in 75.9% of these patients by using a commercial system. High rates of cross-reactivity within the Cupressaceae family and with species of the Taxodiaceae family were recorded with both in vivo and in vitro tests. Conclusions: The use of C. sempervirens in vivo diagnostics should be carefully evaluated until better characterized extracts are developed. In-house-characterized extracts of C. arizonica seem to be more reliable in the diagnosis of Cupressaceae allergy by means of skin prick testing. The sensitivity of commercially available in vitro methods to detect specific IgE to C. sempervirens should be carefully evaluated; nevertheless, valid results can be obtained with some already available immunoassays.