IgA and/or IgG subclass deficiency in children with recurrent respiratory infections and its relationship with chronic pulmonary damage.

Most patients with IgA and/or IgG subclass deficiency are asymptomatic but some may suffer from frequent mainly respiratory infections. The aim of our study was to determine the frequency of IgA and/or IgG subclass deficiencies and the rate of chronic pulmonary damage secondary to recurrent pulmonary infections in these children. Serum IgA and IgG subclass levels were measured in 225 children aged 6 months to 6 years with recurrent sinopulmonary infections (44 with recurrent upper respiratory tract infections, 100 with recurrent pulmonary infections and 81 with recurrent bronchiolitis). In order to determine chronic pulmonary damage due to recurrent infections in patients with recurrent pulmonary infections CT scans of thorax were also obtained. The overall frequency of antibody defects was found to be 19.1%. IgA deficiency was observed in 9.3%, IgG subclass deficiency in 8.4% and IgA + IgG subclass deficiency in 1.4%. The prevalance of IgA and/or IgG subclass deficiency was 25% in patients with recurrent upper respiratory tract infections, 22% in patients with recurrent pulmonary infections and 12.3% in patients with recurrent bronchiolitis (p>0.05). Chronic pulmonary damage in lungs was determined radiologically in 17 of 100 cases with recurrent pulmonary infection. In IgG subclass deficiencies sequel changes, although not statistically significant, were observed five times more frequently than that of IgA deficiencies. CT scans revealed pulmonary sequels in 5 of the 22 (22.7%) patients with recurrent pulmonary infections and immunodeficiency (bronchiectasis in 2 patients with IgG3 deficiency, fibrotic changes in one with IgA deficiency and in one with IgG3 deficiency, bronchiolitis obliterans in one with IgG2 + IgG3 deficiency). On the other hand, pulmonary sequels were observed in 12 patients (15.4%) with normal immunoglobulin levels. Eight of them were bronchiolitis obliterans, 2 of them were atelectasia and 1 of them was bronchiectasia. We therefore suggest that determination of antibody levels and evaluation of pulmonary alterations is crucial in patients with recurrent sinopulmonary infections since the deficiency of antibodies is associated with a greater pulmonary damage.