Kathryn Sutton¹, Megan Yu¹, Jocelyn Jiang¹, Andrew Broadfoot¹, John Quin¹, Karl Baumgart¹

¹Douglass Hanly Moir Pathology, Sydney, Australia

Introduction: Cross-reactive carbohydrate determinants (CCD) are carbohydrate structures present on glycoproteins that may lead to false-positive results in allergen-specific IgE testing. Our laboratory offers three methods of CCD identification - the Allergy Xplorer-2 MacroArray DX^TM (ALEX), Immuno Solid-phase Allergen Chip MicroArray^TM (ISAC) and an individual CCD sIgE on the ImmunoCAP^TM platform.

Method: We conducted a retrospective analysis of allergen-specific IgE test results from three platforms offered in our laboratory over 15 years (2 years of available ALEX data). The proportion of CCD positivity in tests ordered was determined.

Results: Among the tested samples, 144/1679 (8.6%) were positive for CCD (MUXF3) on the ISAC platform, while 18/616 (2.9%) were positive for CCD (Hom s Lactoferrin) on the ALEX platform. Comparatively, on the ImmunoCAP platform, 68 CCD tests were ordered and 16 (23.5%) of these were positive. It is important to note that the CCD identified on ALEX (Hom s Lactoferrin) differs to that identified on the other platforms (MUXF3). Additionally, ALEX uses a CCD blocker.

Conclusion: Our study reveals the prevalence rates of CCD in the Australian population across different allergen-specific IgE testing platforms. These findings emphasise the importance of consideration of CCD interference in allergy diagnostics to minimise the impact of CCD-related false positives and optimise patient management strategies.