Performance of a polymer coated silicon microarray for simultaneous detection of food allergen-specific IgE and IgG₄

Microarray-based component-resolved diagnostics (CRD) has become an accepted tool to detect allergen-specific IgE sensitization towards hundreds of allergens in parallel from one drop of serum. Nevertheless, specificity and sensitivity as well as a simultaneous detection of allergen-specific IgG₄ , as a potential parameter for tolerance development, remain to be optimized.

We applied the recently introduced silicon chip coated with a functional polymer named copoly(DMA-NAS-MAPS) to the simultaneous detection of food allergen-specific IgE and IgG₄ , and compared it with ImmunoCAP and ImmunoCAP ISAC. Inter- and intraslide variation, linearity of signal and working range, sensitivity and application of internal calibrations for IgE and IgG₄ were assessed.

Native and recombinant allergenic proteins from hen's egg and cow's milk were spotted on silicon chips coated with copoly(DMA-NAS-MAPS) along with known concentrations for human IgE and IgG₄ . A serum pool and 105 patient samples were assessed quantitatively and semi-quantitatively with the ImmunoCAP and ImmunoCAP ISAC and correlated with IgE- and IgG₄ -specific fluorescence on silicon microarrays.

Allergen-specific IgE and IgG₄ were detected in parallel using two fluorescent dyes with no crosstalk. Results from the ImmunoCAP correlated better with microarray fluorescence than with ImmunoCAP ISAC except for the allergen ovomucoid. The working range of the silicon microarray for total hen's egg-specific IgE was comparable to the range of 0.1 to >100 kU_A /L of the ImmunoCAP system, whereas for total cow's milk, the silicon microarray was less sensitive. Detectable allergen-specific IgG₄ could be determined only for low concentrations, but still correlated positively with ImmunoCAP results.

We confirmed the ability of the polymer coated silicon microarray to be comparably sensitive to the ImmunoCAP ISAC for various food allergens. This suggests that the copoly(DMA-NAS-MAPS) microarray is a low-cost, self-producible alternative to the commercial ImmunoCAP ISAC in allergy research.