Fas-Fas ligand system in the peripheral blood of patients with renal diseases.

To clarify the role of the Fas-Fas ligand (FasL) system in the peripheral blood from patients with various renal diseases, the Fas and FasL expression on mononuclear cells (MNCs) and serum levels of soluble Fas (sFas) and soluble FasL were investigated. Patients were selected from those with various types of glomerular diseases showing various degrees of renal function. Fas expression on MNCs was analyzed by a FACScan, sFas and soluble FasL were measured with an ELISA kit, and FasL expression on MNCs was counted using a FACScan after a bioassay. Fas-positive MNCs and sFas increased with statistical significance concomitantly with deterioration in renal function. Moreover, there was a significant correlation between them. sFas- and FasL-positive MNCs were significantly correlated with proteinuria. However, the Fas expression percentage on MNCs and/or serum levels of sFas did not correlate with the number of TUNEL-positive cells in the glomeruli. Also, there was no disease specificity in the activation of Fas. These results indicate that Fas expression on MNCs is activated in accordance with the deterioration in renal function without disease specificity, corresponding to the elevation of serum sFas levels to protect against Fas-mediated apoptosis.