In this study, we carried out genomic analyses of blood samples from 184 patients having unexplained recurrent respiratory infections (62 patients), nontuberculous mycobacterial infection (50 patients), aspergillosis (23 patients), and DPB (49 patients). These patients were treated at Tohoku University Hospital, Tenri Hospital, Toranomon Hospital, and National Tokyo Hospital, between 1995 and 2000. The patients with recurrent respiratory infections had at least one episode of pneumonia per year, and showed no apparent abnormalities in the components of the immune system, such as number of circulating WBCs, Ig (IgG, IgA, IgM), and complement system (C3, C4, CH50). The diagnosis of pulmonary nontuberculous mycobacterial infection was established according to the criteria of the American Thoracic Society.17The diagnosis of aspergillosis was made when characteristic radiographic features were found in a patient with serum precipitins positive for Aspergillus species and/or when Aspergillus was isolated from respiratory specimens. The diagnosis of DPB was made according to the criteria established by Homma et al,18 characterized by coarse crackles and rhonchi detected on physical examination together with chest radiographs or CT scan images of characteristic diffuse small nodular lesions and hyperinflation. Patients with underlying pulmonary diseases, a history of immunosuppressive therapy, or an apparent immunologic disorder were excluded. For controls, blood samples were provided by the Blood Donation Center of the Japanese Red Cross Society in Sendai. For BAL fluid (BALF) evaluation, five patients with acute-phase pneumonia (three patients with Pneumocystis carinii pneumonia and two patients with bacterial pneumonia), and five healthy volunteers were newly enrolled at Tohoku University Hospital. The local ethics committee approved this study, and informed consent was obtained from all participants in this study.