Blood and lung mononuclear cell inhibition of fibroblast growth in sarcoidosis.

A defect in mononuclear cell inhibition of fibroblast growth may be important in the pathogenesis of tissue fibrosis in sarcoidosis. To test this hypothesis, supernatants were prepared from unstimulated and phytohemagglutinin (PHA) stimulated peripheral blood and nonadherent lung mononuclear cells of patients with sarcoidosis. The effect of these supernatants on human lung fibroblast log phase growth was compared with the effect of similar supernatants from normal persons and patients with other lung diseases. Supernatants from normal persons and the majority of patients with sarcoidosis had similar effects on fibroblast growth. Unstimulated blood and nonadherent lung mononuclear cells had no consistent effect on fibroblast growth, whereas PHA stimulated cells inhibited fibroblast growth in a dose-dependent fashion. However, unlike that in normal persons, the blood and/or lung mononuclear cells from approximately one third of the patients with sarcoidosis appeared to be activated in vivo because supernatants from these cells inhibited fibroblast growth without in vitro mitogen stimulation. Spontaneous inhibition of fibroblast growth was not seen in supernatants from blood or nonadherent lung mononuclear cells from patients with other lung diseases. Age, sex, lavage cell yield and differential, peripheral lymphocyte count, and percentage of activated T-lymphocytes did not differentiate patients whose mononuclear cells spontaneously inhibited fibroblast growth from those patients whose cells did not. However, patients whose lung mononuclear cells spontaneously inhibited fibroblast growth had fewer pulmonary function abnormalities than did patients whose cells did not.(ABSTRACT TRUNCATED AT 250 WORDS)