Bronchial hyper-responsiveness in selective IgA deficiency

Secretory IgA in mucosal secretions has a broad protective function. The insufficient protection provided by the respiratory mucosa in children with selective IgA deficiency (sIgAD) might facilitate the development of bronchial hyper-responsiveness (BHR) and consequently asthma symptoms. This study was conducted to clarify the prevalence of BHR in sIgAD children and the relationship with atopic status. A cohort of 20 children (group A) aged 6.4-20.1 yr (median: 12.6) with sIgAD (serum IgA < 6 mg/dl) were evaluated for BHR using inhaled hypertonic saline test as well as for atopy by skin prick testing (SPT) to eight common aero-allergens. Seventy other children with normal levels of serum IgA, but sensitized to aero-allergens (group B) and 102 with normal IgA and negative SPTs (group C) were also evaluated. Baseline spirometry demonstrated that forced vital capacity (FVC) values in group A were significantly lower than in C. Forced expiratory volume in 1 s values were similar in all groups, but impairment of the forced expiratory flow over the middle half of the FVC was detected in group B. The prevalence of BHR was similar among group A (30.0%) and group B (35.7%) (p = 0.79) but they differed from group C (5.9%) (p = 0.005). An association between BHR and reported current (p = 0.001) but not lifetime asthma symptoms among group A was also observed. There was no association between atopy and BHR in group A but only to mites' sensitization (p = 0.03). In conclusion, these results indicate that sIgAD constitutes a risk factor for development of BHR but it appears to be related to sensitization to mites.