Eosinophil protein-X in urine showed positive correlation to development of atopy within first 6 years of life

**Chawes BL. Am J Respir Crit Care Med. 2011;doi:10.1164/rccm.201101-0111OC.**

Development of allergic sensitization, nasal eosinophilia and eczema was significantly associated with eosinophil protein-X in the urine of asymptomatic 1-month-old neonates, according to a study.

Urine was collected from 411 healthy infants aged 1 month born to asthmatic mothers in the Copenhagen Prospective Study on Asthma in Childhood (COPSAC) birth cohort.

The urinary eosinophil protein-X (u-EPX) concentration was determined by a double antibody immunoassay in both 1- and 6-month samples. Allergic sensitization, allergic rhinitis and nasal eosinophilia, blood eosinophilia, eczema, and troublesome lung symptoms and asthma were all tested for, but only allergic sensitization, nasal eosinophilia and eczema had a positive correlation with the testing of eosinophil protein-X.

According to the study, “allergic sensitization was determined at age 6 months, 18 months, 4 years and 6 years by measurement of serum-specific [immunoglobulin] E against 16 common inhalant and food allergens by ImmunoCAP assay (Pharmacia Diagnostics).” At age 1 month, u-EPX was associated with increased odds of sensitization. The analysis was significant for food sensitization, borderline significant for aeroallergen sensitization and sensitization to indoor inhalant allergens; however, it was not significant for outdoor inhaled allergens.

Investigated by a nasal scraping when the participants were 6 years old, u-EPX at 1 month was found to be strongly and significantly associated with the results rated according to Meltzer’s semiquantitative scale for nasal eosinophilia.

Using the Hanifin-Rajka criteria, elevated levels of u-EPX were found to have a positive correlation associated with development of eczema early in life. In the first year of life, 27% were diagnosed with eczema and 15% received an eczema diagnosis before age 6 years. With increasing levels of u-EPX at age 1 month, the risk for eczema during the first year of life increased significantly, but not afterward.

“Eosinophil protein-X in urine from asymptomatic neonates is a biomarker significantly associated with later development of allergic sensitization, nasal eosinophilia and eczema during the first 6 years of life,” researchers wrote. “These findings suggest activation of eosinophil granulocytes early in life prior to development of atopy-related symptoms.”

Disclosure: Funding was provided by The Lundbeck Foundation; The Pharmacy Foundation of 1991; the Danish Medical Research Council; the Danish Pediatric Asthma Center; the Danish Lung Association; and Hans Skoubys og hustru Emma Skoubys Fond and Oda Pedersens Legat.

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