A SEARCH FOR MYCOBACTERIAL DNA IN SARCOIDOSIS USING THE POLYMERASE CHAIN-REACTION

The etiology of sarcoidosis is unknown, but mycobacteria have been con sidered as a possible etiologic agent. The authors used the polymerase chain reaction (PCR) to search for mycobacterial DNA in paraffin-embe dded granulomatous tissues from patients with sarcoidosis. The target sequence used for PCR amplification is a 383-base pair segment of the gene encoding the 65 kD mycobacterial surface antigen. This assay can detect Mycobacterium tuberculosis and atypical mycobacteria in archiva l material. Its sensitivity, which is superior to Ziehl-Nielsen staini ng for acid-fast bacilli, is 1 bacterium per 2500 cells. Ten sarcoidos is blocks and 10 normal controls were negative with mycobacterial PCR but positive with beta-actin PCR, indicating the presence of amplifiab le DNA. Mycobacterial PCR gave positive results for six acid-fast baci lli stain/culture-positive blocks from patients with tuberculosis. The se results indicate that sarcoidosis probably does not represent an ac tive mycobacterial infection. These data also suggest that mycobacteri al PCR is helpful in differentiating tuberculosis and sarcoidosis.