Differential display of messenger RNA expressed in bronchoalveolar lavage cells in pulmonary sarcoidosis patients.

Sarcoidosis is a systemic granulomatous disease of unknown origin. To clarify its pathogenesis, we searched for known or unknown genes which are specifically expressed in sarcoidosis. Bronchoalveolar lavage (BAL) cells from 18 patients with sarcoidosis and 8 patients with various lung diseases were analyzed by differential display method. mRNA was extracted from BAL cells and reverse transcribed with 12 kinds of anchored primer, which theoretically cover all mRNAs, followed by polymerase chain reaction (PCR) with the anchored primer and a 10-mer arbitrary primer. PCR products were displayed on a polyacrylamide gel and fragments showing characteristic alterations in intensity between sarcoidosis and other patients were extracted, sequenced, and compared against Genbank and EMBL DNA data bases. One fragment was detected with specifically increased intensity and another disappeared in patients with sarcoidosis. These fragments were likely derived from unknown genes. CD44 and tumor necrosis factor (TNF-alpha) cDNA sequences were also detected as fragments commonly expressed in sarcoidosis. The cloned fragments with specifically increased or decreased intensity in sarcoidosis may provide important information on the pathogenesis of sarcoidosis, and the display pattern implies the potential usefulness of this method as a tool for diagnosis of the disease.