PERIPHERAL-BLOOD MONONUCLEAR-CELLS OF PATIENTS WITH SYSTEMIC-SCLEROSIS PRODUCE INCREASED AMOUNTS OF INTERLEUKIN-6 BUT NOT TRANSFORMING GROWTH-FACTOR-BETA-1

Objective. To assess the ability of peripheral blood mononuclear cells (PBMC) of patients with systemic sclerosis (SSc) to produce interleuk in 6 (IL-6), transforming growth factor beta 1 (TGF-beta 1), to identi fy the IL-6 producer cells in the in vitro model, and to correlate the se data with the clinical evidence of our patients. Methods. We used-a sandwich ELISA to quantitate IL-6 and TGF-beta 1 levels in sera, plas ma, and supernatants, and an immunofluorescence technique to evaluate IL-6 producing cells in our patients. Results. IL-6 was detected in se ra from 8 of 20 patients and no controls (p < 0.05). A significant inc rease of IL-6 production was observed in both spontaneous and phytohem agglutinin (PHA) induced cultures of PBMC from patients with SSc vs co ntrols. No differences in TGF-beta 1 production were observed, either in sera or supernatants, between patients and controls. A significant increase of IL-6 synthesizing cells was observed after 3 h of PHA stim ulation in patients vs controls (p < 0.05). Conclusion. Spontaneous IL -6 production and the higher number of IL-6 producing cells in patient s with SSc suggest that these cells have been already primed in vivo. The absence of PBMC primed for TGF-beta 1 production supports the hypo thesis that cells other than lymphocytes produce and secrete this cyto kine in the skin of patients. Higher serum levels of IL-6 observed in a subset of patients did not correlate with either severity or duratio n of disease.