Enhanced mRNA expression of Th1 cytokines and IL-12 in active pulmonary sarcoidosis

Background and aim of the work: Active sarcoidosis is considered to be a Th 1 dominant condition. We examined whether Th1 cytokines are highly expresse d at inflammed lesions of Japanese patients with sarcoidosis. Methods: To i nvestigate the mRNA expression of Th1 cytokines and IL-12 in sarcoid BAL ce lls, we used semiquantitative reverse transcription - polymerase chain reac tion method. Results: The mRNA expressions of Th1 cytokines (IFN-gamma and IL-2) in active sarcoid BAL cells were significantly elevated as compared w ith those in healthy volunteers. The proportion of positive IL-4 mRNA expre ssion in sarcoid BAL cells was not significantly higher than that in health y volunteers. Further, there was no significant difference in IFN-gamma mRN A levels between the groups positive and negative for IL-4 mRNA expression. Although the proportion of positive expression of IL-12 mRNA in active sar coid BAL cells was not significantly higher than that in healthy volunteers , the group positive for IL-12 mRNA expression had significantly elevated l evels of IFN-gamma mRNA than did the negative group. Conclusions: These res ults may indicate that IL-12 induces IFN-gamma expression and subsequent Th 1 dominant condition in Japanese patients with sarcoidosis.