TNF alpha mRNA, but not IL-1 beta, is differentially expressed in lung macrophages of patients with active pulmonary sarcoidosis.

Abstract

In pulmonary sarcoidosis or experimental granuloma formation, interleukin-1 beta (IL-1 beta) or tumor necrosis factor alpha (TNF alpha) seem to play important roles during the inflammatory process. In order to examine whether IL-1 beta or TNF alpha mRNA expression in lung macrophages relates to disease activity or clinical course, ten cases with pulmonary sarcoidosis were divided into two groups: five cases with disease duration of more than 10 years (14.6 +/- 4.4 yrs; group A), and 5 cases with a duration of less than 3 years (1.7 +/- 1.1 yrs; group B). All cases showed both abnormal chest X-rays and elevated serum angiotensin converting enzyme activities. We compared these ten cases with 12 healthy subjects (6 nonsmokers: NS and 6 current smokers: S), and 5 cases with idiopathic pulmonary fibrosis (IPF) as disease control. Lavage macrophages were purified using the rosette forming method followed by plastic adhesion for one hour. Thereafter, RNA was extracted according to the AGPC method and amplified by the reverse transcription-polymerase chain reaction (RT-PCR). The results showed that IL-1 beta mRNA was detected in all samples studied, but TNF alpha mRNA expression was different among the groups: 5/5 (100%) in group A, 1/5 (20%) in group B, 5/5 (100%) in IPF, and 12/12 (100%) in healthy subjects. A constitutive expression was seen in healthy controls. On the other hand, no detection of TNF alpha mRNA was shown in pulmonary sarcoidosis. This fact may relate to a spontaneous regression of inflammation in sarcoidosis, as a substantial number of cases in group B may in time regress spontaneously.