MYCOBACTERIUM-TUBERCULOSIS DNA IN TISSUES AFFECTED BY SARCOIDOSIS

Background-Although some studies have reported the presence of Mycobac terium tuberculosis (MTb) DNA in tissues affected by sarcoidosis, the data are conflicting. The aim of this study was to collect prospective ly tissue from patients with sarcoidosis in whom tuberculosis had been excluded, and to use polymerase chain reaction (PCR) to search for DN A sequences specific for MTb. Methods-Fresh tissue samples (node or lu ng biopsy) taken from 23 patients with newly diagnosed sarcoidosis, 10 with other respiratory disease, and four patients with culture positi ve tuberculosis were analysed using PCR to amplify a 123 bp fragment o f IS6110, the insertion element present in MTb, and nested PCR to furt her amplify an 85 bp sequence within the 123 bp product. DNA was also extracted from formalin fixed tissue from eight additional patients wi th sarcoidosis. Results-MTb DNA was not detected in any of the tissue samples from patients with sarcoidosis or other respiratory disease bu t was found in all four patients with tuberculosis. Conclusions-This s tudy has shown the absence of MTb DNA in lymph node and lung biopsy sa mples from patients with sarcoidosis. MTb is therefore unlikely to be a factor in the pathogenesis of this disease.