Basophil responsiveness in patients with insect sting allergies and negative venom-specific immunoglobulin E and skin prick test results

P>Background Current guidelines do not adequately address the question of how best to manage patients with a convincing history of insect allergy, but negative venom-specific IgE and skin test results. Methods Forty-seven patients out of a total of 1219 (4%), with a positive history of sting allergy, were recruited over a period of 4.5 years. All recruited patients had a convincing history of a severe or a life-threatening anaphylactic reaction of Mueller grade II-IV (median grade III) after Hymenoptera sting, but negative venom-specific IgE and skin prick test results. Diagnostic work-up was prospectively followed by the CD63 basophil activation test and by intradermal skin testing. A control group of 25 subjects was also assessed. Results Thirty-five out of 47 (75%) patients demonstrated a positive basophil CD63 response after stimulation with bee and/or wasp venom. Intradermal venom skin tests were performed for 37 patients, 17 (46%) of whom showed positive results. Out of 20 patients who demonstrated negative intradermal test results, 12 patients showed a positive CD63 response (60%). In contrast, out of 9 patients who showed a negative CD63 response, only one was detected by intradermal testing (11%). In the control group, only two out of 25 (4%) subjects displayed a positive basophil response and/or intradermal test. Conclusion Here we show that, in complex cases with inconclusive diagnostic results, the CD63 activation test could be particularly useful and more sensitive than intradermal skin testing. Cite this as: P. Korosec, R. Erzen, M. Silar, N. Bajrovic, P. Kopac and M. Kosnik, Clinical & Experimental Allergy, 2009 (39) 1730-1737.