Interleukins in pulmonary sarcoidosis. Dissociative correlations of lung interleukins 1 and 2 with the intensity of alveolitis.

To investigate whether interleukins are involved in the formation of alveolitis in pulmonary sarcoidosis, interleukin-1 (IL-1) production by LPS-stimulated alveolar macrophages (AM) and interleukin-2 (IL-2) production by PHA-stimulated lung and blood T-cells were determined in 35 untreated patients with pulmonary sarcoidosis. The amount of IL-1 produced by AM (BAL IL-1) was significantly increased in patients with pulmonary sarcoidosis compared with that in 18 control subjects. BAL IL-1 showed a significant positive correlation with the intensity of alveolitis assessed by the proportion of lymphocytes in bronchoalveolar lavage fluid (BALF) and the absolute number of lymphocytes per milliliter of BALF. However, the amount of IL-2 produced by lung T-cells (BALT IL-2) showed a significant negative correlation with the intensity of alveolitis. BALT IL-2 was significantly lower than the amount of IL-2 produced by blood T-cells (PBT IL-2). There was no correlation between PBT IL-2 and the intensity of alveolitis. These results suggest that IL-2 contributes to the formation and maintenance of alveolitis in pulmonary sarcoidosis, whereas IL-2 production by lung T-cells is suppressed to down-regulate the enhanced immune processes at the site of disease. The possibility that this hyporesponsiveness of lung T-cells to PHA has resulted from the modulation of the T3-T cell receptor complex remains to be determined.