Serum levels of soluble fas in patients with multinodular goiter.

Fas is a cell-surface receptor responsible for induction of apoptosis in human thyrocytes upon interaction with Fas Ligand. Fas protein expression on thyroid cells and Fas-mediated apoptosis is decreased in multinodular goiter (MNG) resulting in thyroid cell proliferation. The soluble form of Fas (sFas) produced by alternative mRNA splicing may inhibit Fas-Fas Ligand binding and apoptosis. The aim of this study was to examine whether sFas is differentially expressed in multinodular goiter (MNG), which is associated with decreased Fas-mediated apoptosis.,We determined serum sFas levels using enzyme-linked immunosorbent assay (ELISA) in 42 patients with MNG and 23 normal controls.,Serum sFas levels were increased in patients with MNG (7.47 +/- 2.55 ng/ml) compared to normal controls (2.26 +/- 0.9 ng/ml). Levels of sFas were not significantly correlated with age, sex or clinical parameters, such as serum levels of FT4 or TSH.,Increased sFas in MNG may indicate increased expression of alternatively spliced Fas mRNA variant and decreased expression of cell-surface Fas protein, and may enhance thyroid cell proliferation by protecting thyroid cells from Fas-mediated apoptosis.