Allergen specific IgE titers are suppressed by increased IgG4 levels when analyzed by multiplex molecular allergen chip but not by fluoroenzyme immunoassay

RATIONALE: Induction of a specific IgG4 response suppressing the IgE-mediated symptoms is a key element in the protective effect of allergy specific immunotherapy (ASIT). IgE measurement by fluoroenzyme immunoassay (FEIA) is a standard procedure for allergy diagnosis. It is supplemented by a chip-based single allergen array which may have different dynamics. METHODS: 24 subjects suffering from allergic rhinitis were randomized to receive standard subcutaneous ASIT (n5 18) or to an open control group (n56). Allergen specific IgE and IgG4 were measured at baseline and when reaching maintenance dose by using both FEIA and the multiplex molecular allergen chip (MMAC) assay. Data are presented as mean with 95% CI. RESULTS: ASIT increased allergen specific IgG4 levels, measured both by MMAC (from 0,3 to 5,0 ISAC specific units (ISU) (D: 2,7-6,7 ISU; p=0,0001) and FEIA (from 0,1 to 5,2 mg/l, D: 2,3-7,9 mg/ml; p=0,0006). Specific IgE increased from 23,0 to 48,8 kU/l when measured by FEIA (D: 4,4-47,2; p=0,01) while it decreased from 21,4 to 2,5 ISU (D:-10,0;-27,8; p=0,0002) when measured by MMAC. No significant changes occurred in the control group. CONCLUSIONS: FEIA measurements indicate that IgG4 and IgE increase during ASIT updosing. In contrast, when IgE was measured by a MMAC assay, a decrease in IgE seems to indicate successful ASIT. This may be owing to an inhibition of IgE-binding in vitro in the MMAC assay, possibly reflecting functional IgE inhibition in vivo. The chip-based measurements may thus be useful in monitoring the clinical effect of ASIT.