THE ROLE OF HOUSE DUST MITE SENSITIZATION IN GALACTO-OLIGOSACCHARIDE (GOS) ALLERGY IN SINGAPORE

Abstract

Background: Galacto-oligosaccharide (GOS), a prebiotic supplemented in formula milk, has been reported to trigger anaphylaxis in Southeast Asia. These reactions occurred on first ingestion of GOS, and were shown to be IgE mediated. Hypothesis: In view of the clinical characteristics of GOS allergy, a primary sensitizer(s) is likely. This study aims to identify the primary sensitizer(s) of GOS allergy by screening for IgE sensitization to common environmental allergens in GOS allergic patients and for cross reactive IgE to GOS. Results: All GOS allergic subjects (n=33) were sensitized to Blomia tropicalis (Blo t), a unique allergen to the tropics. Using IgE ELISA inhibition assay, it was shown Blo t extract was able to inhibit GOS-specific IgE in a dose dependent manner. IgE cross-reactivity between the glycoallergens in Blo t extract and GOS was demonstrated by the loss of GOS-specific IgE inhibition ability of deglycosylated Blo t extract and comparable GOS-specific IgE inhibition ability of protein digested Blo t extract. Conclusion: Blo t is one of the primary sensitizer(s) for GOS allergy in our patients, and may explain its unique geographical distribution.