Propionibacterium acnes DNA detected in bronchoalveolar lavage cells from patients with sarcoidosis

The causes of sarcoidosis are unknown. Propionibacterium acnes is so far the only bacterium to be found in sarcoid lymph nodes. We attempted to detect P. acnes DNA in cells recovered by bronchoalveolar lavage (BAL) from patients with sarcoidosis.

BAL cells from 30 patients with histologically proven sarcoidosis and 30 controls with other lung diseases were examined by a nested polymerase chain reaction (PCR) for 16S rRNA of P. acnes. BAL cells from three recent sarcoid patients and two control patients were also examined by in situ PCR to locate P. acnes DNA. Clinical findings in sarcoid patients with and without positive results by PCR were compared.

P. acnes DNA was detected in BAL cells from 21 (70%) sarcoid patients and 7 (23%) control patients. In situ signals of P. acnes DNA were detected in the cytoplasm of 0.2% to 2.8% of alveolar macrophages from sarcoid patients, but from no cells of the control patients. Gallium-67 uptake by lung parenchyma was found in about half of the sarcoid patients with P. acnes DNA, but in none of the other sarcoid patients. More of these patients with such DNA had lung parenchymal shadows in chest X-ray films and were in more advanced stages of the disease than the other sarcoid patients.

Detection of P. acnes DNA in BAL cells was significantly more common in the patients with confirmed sarcoidosis. Detection was associated with some indices of disease activity in the lung.