Plasma soluble Fas ligand concentration: Decrease in elderly men and increase in patients with gastric carcinoma

Fas ligand (FasL), which induces apoptosis against Fas-expressing cells, has been found to be expressed on various cell types including cancer cells. Membrane-bound FasL is cleaved to release soluble FasL (sFasL). Although serum or plasma sFasL concentration has been reported to increase in various diseases, sFasL concentration in healthy normal persons has not been fully studied. There have been few reports on sFasL concentrations in patients with carcinomas. We measured plasma sFasL concentrations using an enzyme-linked immunosorbent assay in 155 healthy volunteers (70 males and 85 females with an average age of 41.5±15.4) and 112 patients with gastric carcinoma (76 males and 36 females with an average age of 62.3±11.5). A significant negative correlation existed between age and plasma sFasL concentration in healthy volunteers. sFasL concentrations in males were significantly lower than those in females. Plasma sFasL levels were significantly higher in patients with gastric carcinoma than in healthy volunteers when male subjects aged 50 or older were analyzed, although no significant difference existed between the groups in the age bracket of 35 to 49. Male patients aged 50 or older with stage 1B or 2 tumors showed significantly higher plasma sFasL concentrations than those with stage 1A tumors or those with stage 3 or 4 tumors. In conclusion, age- and gender-matched controls should be used when plasma sFasL concentration is investigated. The origin and physiological or clinical significance of plasma sFasL in healthy volunteers and gastric cancer patients remain to be clarified.