High serum soluble interleukin-2 receptor concentrations in elderly individuals and smokers.

The effects of sex, age, and smoking on the serum concentrations of soluble interleukin-2 receptor (sIL-2R) were investigated in 83 healthy subjects. No sex-related difference was found. The correlation between age and the serum sIL-2R concentration was weak, but significant, in the nonsmokers (r = 0.30, n = 50, p < 0.05). The serum sIL-2R concentration was significantly higher in smokers than in nonsmokers (41.0 +/- 2.8 pM (mean +/- SEM), n = 33, vs. 31.9 +/- 1.0, n = 50, p < 0.005). These results suggest that age and smoking habits should be taken into consideration when interpreting the serum sIL-2R concentration, although the mechanism by which sIL-2R concentrations are altered remains unknown at present.