The incidence of nontuberculous mycobacterial lung disease (NTM-LD) is increasing worldwide and in Eastern Asia. NTM-LD leads significant morbidity and mortality, around 25% within 5 years, but the treatment rate is low because the course of NTM-LD is indolent, especially in nodular-bronchiectatic (NB) form. However, there is no biomarker proven for predicting the progression in NB form of NTM-LD. Recently, it has been reported that the ratio of membrane-form programmed death-1 (PD-1) expressed T cells increased in patients with NTM-LD and it was associated with disease severity and progression. The mechanism has been speculated as a "immune exhaustion". In contrast to PD-1 expressed in cell membrane, soluble-form PD-1 is another biomarker that can be easily detected in serum. We recently reported that soluble PD-1 significantly correlated with cavitary lesion and disease progression in patients with NB-form NTM-LD in Taiwan. However, this has not been validated in other countries and ethnicities. Furthermore, the usefulness of soluble PD-1 in diagnosis and predicting mortality warrants further studies.

The incidence of nontuberculous mycobacterial lung disease (NTM-LD) is increasing worldwide and in Eastern Asia. NTM-LD leads significant morbidity and mortality, around 25% within 5 years, but the treatment rate is low because the course of NTM-LD is indolent, especially in nodular-bronchiectatic (NB) form. However, there is no biomarker proven for predicting the progression in NB form of NTM-LD. Recently, it has been reported that the ratio of membrane-form programmed death-1 (PD-1) expressed T cells increased in patients with NTM-LD and it was associated with disease severity and progression. The mechanism has been speculated as a "immune exhaustion". In contrast to PD-1 expressed in cell membrane, soluble-form PD-1 is another biomarker that can be easily detected in serum. We recently reported that soluble PD-1 significantly correlated with cavitary lesion and disease progression in patients with NB-form NTM-LD in Taiwan. However, this has not been validated in other countries and ethnicities. Furthermore, the usefulness of soluble PD-1 in diagnosis and predicting mortality warrants further studies. Moreover, it is worthwhile to measure soluble PD-1 in bronchoalveolar lavage to explore local immune pathogenesis of NTM-LD. Therefore, we apply this project to investigate the role of soluble PD-1 in NTM-LD through a multi-country cooperation.

Inclusion Criteria:

• Age ≥ 20 years
• NTM-LD: (N=250) Diagnosis is made on the basis of the guidelines produced by the American Thoracic Society.Patients have pulmonary symptoms with identified chest image and fit with the microbiology criteria.
• NTM pulmonary colonizers and others: (N=100) Those without fulfilling the diagnostic criteria but having at least one set of positive sputum for MAC or patients infected with NTM other than MAC species.
• Pulmonary tuberculosis (TB): (N=100) Those with respiratory specimen culture positive for Mycobacterium tuberculosis or typical TB pulmonary pathology.
• Healthy control (N=50)

Exclusion Criteria:

• Patients who have acquired immunodeficiency syndrome

Patients with NTM-LD at National University Hospital, Taiwan ,Fukujuji Hospital, Japan and Seoul National University, Korea.