BACKGROUND Pulmonary sarcoidosis is characterised by a mononuclear alveolitis with a predominance of CD4+ T cells and macrophages. We determined the intracellular expression of interferon (IFN)γ, interleukin (IL)-2, tumour necrosis factor (TNF)α, IL-4, IL-5 and IL-10 in CD4+ and CD8+, naive and memory lymphocytes from blood and bronchoalveolar lavage (BAL) fluid using three colour flow cytometry.

RESULTS Significantly more T cells expressed Th1 than Th2 type cytokines in both BAL fluid and peripheral blood samples, regardless of clinical presentation. Significantly greater proportions of T cells secreted Th1 type cytokines in BAL fluid than in peripheral blood. Th1 type cytokines were more frequently expressed by peripheral and alveolar T cells in acute disease than in chronic disease. There were no significant differences between CD4+ and CD8+ T cells. Concerning naive and memory lymphocytes, significantly higher CD45RO:CD45RA ratios were found in BAL fluid than in blood, and increased expression of Th2 type cytokines was found in peripheral compared with alveolar memory T cells.

CONCLUSIONS Our data support the immunopathogenetic concept of Th1/Th2 imbalance and compartmentalisation in pulmonary sarcoidosis and suggest that the cytokine patterns change during the course of disease. Expression of Th2 type cytokines in memory lymphocytes is decreased in the alveolar compartment compared with peripheral blood.