Cross-reactive carbohydrate determinant interference in cellulose-based IgE allergy tests utilizing recombinant...

Area of Science:

• Allergy diagnostics
• Immunology
• Biochemistry

Background:

• Cross-reactive carbohydrate determinants (CCDs) are epitopes on glycoproteins that cause IgE antibody cross-reactivity, potentially interfering with allergy diagnostics.
• Component Resolved Diagnosis (CRD) uses recombinant, non-glycosylated components to avoid CCD detection, but CCD-specific IgE (sIgE) may still bind to cellulose-based assay matrices.
• This study investigates CCD-sIgE interference on a common automated in vitro sIgE platform using a cellulose-based matrix.

Purpose of the Study:

• To investigate the prevalence of CCD-sIgE interference in a commonly used automated in vitro sIgE platform.
• To evaluate the impact of CCD-sIgE on diagnostic accuracy when using non-glycosylated recombinant components immobilized on a cellulose-based matrix.
• To compare the performance of a cellulose-based assay with a non-cellulose based assay in the presence of CCD-sIgE.

Main Methods:

• Sera from patients sensitized to peanut, silver birch, and timothy grass were tested for CCD-sIgE on ImmunoCAP/Phadia and NOVEOS platforms.
• Positive CCD-sIgE sera were analyzed against non-glycosylated recombinant components on the ImmunoCAP solid phase, with and without a soluble CCD inhibitor.
• Comparative analysis was performed using the NOVEOS assay, a non-cellulose based automated sIgE assay.

Main Results:

• 35% of the tested sensitized population showed positive CCD-sIgE.
• 17% of those with positive CCD-sIgE yielded false-positive results on the ImmunoCAP assay (cellulose-based) with non-glycosylated components, which were negative on NOVEOS.
• CCD interference predominantly affected low-positive IgE results (0.35-3.00 kUA/L).

Conclusions:

• Cellulose matrix-based allergosorbents in sIgE assays can lead to falsely elevated results due to CCD-sIgE.
• Non-glycosylated recombinant allergenic components on cellulose matrices do not eliminate the risk of CCD detection.
• Mitigation strategies include adding a soluble CCD inhibitor or using non-cellulose based sIgE assays like NOVEOS.