Presence of mRNA for interferon-gamma (IFN-gamma) in blood mononuclear cells is associated with an active stage I sarcoidosis.

Peripheral blood mononuclear cells (PBMC) and bronchoalveolar lavage (BAL) cells obtained from sarcoidosis patients were investigated for the presence of mRNA for IFN-gamma. RNA was extracted from freshly obtained cells. In 12 cases PBMC were studied and in seven cases BAL cells were also available for concomitant investigation. In eight patients mRNA for IFN-gamma was present in blood and was significantly associated with stage I disease (P = 0.030). By comparison, BAL cells were less frequently positive for IFN-gamma transcripts (P = 0.039). Only one patient had simultaneous expression of IFN-gamma gene in blood and BAL cells. All other patients including four positive in blood were negative in BAL. The presence of IFN-gamma transcripts in PBMC was significantly associated with the capacity of these cells to generate IFN-gamma in unstimulated cultures. PBMC from patients showing IFN-gamma mRNA in blood were frequently high IFN-gamma producers in anti-CD3 MoAb-stimulated cultures.