In vitro diagnosis of cypress pollen allergy by using cytofluorimetric analysis of basophils (Basotest)

Background: Cupressaceae pollen allergy is a worldwide pollinosis, but its in vitro diagnosis is notoriously difficult, The Basotest is a newly available in vitro test for the detection of allergen-specific IgE based on the level of cellular activation of basophils by using flow cytometry, Objectives: The Basotest was compared with the measurement of cypress pollen-specific IgE in highly selected patients. Methods: We analyzed 34 patients allergic to cypress pollen selected on the basis of a suggestive clinical history and positive skin test and nasal challenge responses to cypress pollen extract. We also analyzed 8 patients with positive skin test responses to cypress pollen extract who did not present symptoms during the pollen season (intermediate group) and 33 control subjects. Sensitivity, specificity, and efficiency of the Basotest and serum specific IgE levels measured by using the CAP System were determined in patients allergic to cypress pollen. Histamine release was studied in a selected group of patients. Results: The Basotest was more sensitive (91.2%) than the CAP System (76%) for the in vitro diagnosis of cypress pollen allergy. A dose-response curve was observed in basophils obtained from patients allergic to cypress pollen. There were no false-positive results with either test (specificity 100%). The results of the Basotest or those of the CAP System did not correlate with the patients' in vivo threshold sensitivity assessed by skin tests and nasal challenge. Conclusions: The Basotest was found to be an effective diagnostic test in patients allergic to cypress pollen.