FIBROBLASTS AS TARGET AND EFFECTOR-CELLS IN JAPANESE PATIENTS WITH SARCOIDOSIS

Fibroblasts play a crucial role in :progressive lung fibrosis, acting not only as target cells but also as effector cells. To clarify these functions in sarcoidosis, lung fibroblasts from Japanese sarcoid patie nts were studied for their proliferative capacity and cytokine product ivity. Fibroblasts were cultured from transbronchial lung biopsy speci mens from seven patients with sarcoidosis. As a comparison, fibroblast s from open lung biopsy specimens of four patients with idiopathic pul monary fibrosis (IPF) were studied. For controls, fibroblasts were cul tured from specimens of normal resected lung tissue of five patients w ith localized lung cancer. The proliferative activity of cultured fibr oblasts from patients with sarcoidosis was highest among the three gro ups (p < 0.05). However. the proliferative capacity in all groups was suppressed when fibroblasts were cultured with interleukin-1 beta (IL- 1 beta). No significant differences were noted in the degree of inhibi tion among the three groups. Addition of interferon-gamma (IFN-gamma) also resulted in inhibition of fibroblast growth in all groups, but th e degree of inhibition was significantly greater in both the sarcoid a nd IPF groups than in controls (p < 0.05). The amount of interleukin-6 (IL-6) in the culture supernatants from sarcoid fibroblasts coculture d with IL-1 beta was significantly higher than in controls. Sarcoid fi broblasts are not only proliferatively active but also possess effecto r cell function to produce cytokines. IL-6 may enhance the immunologic reaction to sarcoidosis and cause the disease to become chronic. IFN- gamma suppresses proliferation of sarcoid fibroblasts and may prevent fibrotic changes of the lungs in che Japanese sarcoid patients.