Impaired interferon gamma production by peripheral blood mononuclear cells and effects of calcitriol in pulmonary sarcoidosis

Pulmonary sarcoidosis (S) is a granulomatous disease of unknown etiology characterized by spontaneous release of cytokines and 1,25-dihydroxyvitamin D3 (calcitriol) at the sites of granulomatous reaction. Stimulated by our previous findings that high levels of interferon-gamma (IFN-gamma) occur in this disease and that calcitriol reduces IFN-gamma production by peripheral blood mononuclear cells (PBMC) from normal subjects, we designed the present study to evaluate IFN-gamma production and the effect of calcitriol on the release of this cytokine by PBMC in S patients. The cells were stimulated with staphylococcal enterotoxin A (SEA) and A23187 calcium ionophore. Our results show that SEA- and A23187-stimulated PBMC from patients with S released significantly less IFN-gamma than those from control subjects. Calcitriol at 10(-6) M and 10(-9) M concentrations reduced IFN-gamma production by SEA-stimulated PBMC but this inhibitory effect was lower in S patients than controls. With A23187 we observed different behaviour at the various doses: at low doses calcitriol was as effective as in controls, but at 10(-6) M it was significantly less inhibitory in S than in healthy subjects.