Decreased risk for atopic disorder associated with highly hyperreactive tuberculin skin test reaction in children and adolescents

Background It is speculated that the exposure to Mycobacterium tuberculosis, either by infection or by Bacillus Calmette‐Guérin vaccination, may inhibit the onset of atopy by the modification of immune profiles leading to a shift of TH1/TH2 balance to the TH1 side. Objective One hundred eighty‐six patients hyperreactive at tuberculin skin test (TST) were examined in order to investigate the prevalence of atopic disorder, particularly referring to the association between the size of the TST induration and the prevalence of sensitization and manifest atopic disorder. Methods The study consisted of a family history record, patients' medical history assessment and clinical examination, skin prick test (SPT), serum total and allergen‐specific IgE (sIgE) measurement and eosinophil count. Results Atopic disorder was present in 49 (26.3%) patients tested. No significant difference between the groups based on the TST induration size (15–24 mm vs. ≥25 mm) was found for gender distribution, family atopy history, total IgE measurement, eosinophil count, positive SPT, and the presence of sIgE. A significant difference was found for the age median (14.0 years vs. 13.0 years), childhood atopy record, and manifest atopic disorder. No association between the size of the TST induration and the incidence of allergic sensitization was demonstrated. However, a significant inverse association between the size of the TST induration and manifest atopic disorder was demonstrated. Conclusion In patients highly hyperreactive at TST, the size of the induration is inversely associated with manifest atopic disorder. Pediatr Pulmonol. 2009; 44:701–705. © 2009 Wiley‐Liss, Inc.