An 18 year Follow-up of Allergy Development Findings of Nasal Markers of Allergic Inflammation

Abstract: Background: In addition to the family history of allergy (FH), there is a need o find objective markers of allergy development as early in life as possible in order to focus preventive measurements on high risk infants. Rhinitis problems are common causes to morbidity in adults due to allergic as well as non-allergic mechanisms. Accurate diagnoses are essential for decisions of optimal management of the patients, but in non-allergic rhinitis groups there are no objective tests to verify the diagnosis, if this is needed.Aims: The primary aim was to evaluate the occurrence of nasal metacromatic (MC) cells during infancy as predictors for allergy development in a group of high risk subjects from birth up to 18 years of age. Additional aims were to find and evaluate nasal markers with ability to differentiate between allergic rhinitis with and without current allergen exposure from normal controls.Subjects and methods: New-borns (n = 67) with and without family histories of allergy were included, and during the first 18 months of life occurrence of nasal MC could be evaluated in 64 infants (33 positive/31 negative MC findings). The cohort was followed up for allergy development at the ages of 18 months, 6 years and 18 years. Nasal markers as MC, nasal NO, nitrite/nitrate in nasal lavage and acoustic rhinometry at the 18-years follow-up were related to the allergic manifestations at this age.Results: Positive nasal MC findings during infancy predicted allergy development up to 18 years of age in 31/33 subjects (94 %), as compared to 37/44 with positive FH (84 %). Negative MC findings during infancy did not exclude the risk, as 15/31 developed allergy (48 %). At the 18-years follow-up the numbers of individuals with demonstrable MC were significantly higher (p = 0.01) in the group of individuals with allergy symptoms (16/30) compared to the group of individuals with no allergy (1/12). Nasal NO levels, nitrite/nitrate concentrations in nasal lavages and acoustic rhinometry did not differentiate the allergic groups from the normal group.Conclusions: Positive nasal MC findings during infancy predicted allergy development up to 18 years of age, and the cell findings often preceded the allergic symptoms. The marker can not be used as a single predictor of allergy development due to negative MC findings in a high proportion of allergic subjects. Positive MC findings combined with positive FH resulted in the best the risk evaluation. Differences between groups with and without current allergen exposure and healthy controls were not found by means of acoustic rhinometry, nasal MC, nasal NO or nitrites/nitrates levels. Further research to find reliable nasal markers is needed.