Incidence of Immunoglobulin G Subclass Deficiencies in Patients with Bronchiectasis and the Clinical Characteristics of Patients with Immunoglobulin G Subclass Deficiency and Bronchiectasis

Background: There are various etiologies causing bronchiectasis, but the cases without definite causes account for a quite high proportion. It is also uncertain that immunoglobulin G subclass deficiency (IgGSD) is associated with bronchiectasis. Therefore, we tried to measure the frequency of IgGSD in patients with bronchiectasis of unclear etiology, and to observe the clinical features of those patients with bronchiectasis and IgGSD. Methods: For the outpatients of a university hospital who were diagnosed as bronchiectasis by chest CT, we produced comprehensive history taking and physical examinations, and finally selected 31 patients with bronchiectasis of unclear etiology. Results: Two patients had total immunoglobulin G deficiency. The frequency of IgGSD was comparatively high (n=14). When we compared IgGSD group to normal immunoglobulin G subclass group, there were no significant differences in sex, age, and the frequency of sinusitis, bronchial asthma, and the abnormal lung function. Conclusion: In cases of bronchiectasis without definite causes, it can be considered to measure the level of immunoglobulin G subclass. It is also probably worthwhile to further evaluate the relationship between IgGSD and bronchiectasis.