Plasma level of interleukin-6 and interleukin-8 in the elderly

It is believed that changes in the serum level of cytokines (e.g. IL-6) are natural consequence of physiological aging. On the other hand, increased level of proinflammatory cytokines (Il-6 and IL-8) occurs during inflammation. The aim of the study was to estimate serum levels of IL-6 and IL-8 to check if the possible increase in IL-6 in elderly is caused by diseases rather than by aging. The study involved 30 healthy elderly (Group B: age 71.1 +/- 5.5 years; range 65-89 year) and 29 healthy young subjects (Group K: age 27.0 +/- 4.2 years, range: 21-37 years). In every subject serum level of IL-6 and IL-8 was assessed with immunoassay techniques using ELISA. The amount of subjects with the detectable level of IL-6 was comparable in both in group B and K (38.5% vs. 27.6%). The IL-6 level was almost 5 times higher in older group but the difference was not statistically significant (10.89 +/- 22.65 vs. 2.17 +/- 4.94). Similarly, the amount of subjects with the detectable level of IL-8 was comparable in both in B and K group (20.7% vs. 18.2%) and the IL-8 level was almost 5 times higher in older group vs. younger one but the difference was not statistically significant (9.61 +/- 20.89 vs. 2.65 +/- 6.09 pg/ml). In both studied groups, subjects with detectable level of IL-6 (Group B1 and K1, respectively) had also higher IL-8 level in comparison to subjects with non-detectable IL-6 (Group B2 and K2) (B1: 18.06 +/- 27.15 pg/ml, B2: 4.33 +/- 14.43 pg/ml, p = 0.052 and K1: 7.65 +/- 8.69 pg/ml, K2: 0.74 +/- 3.41 pg/ml, p < 0.01). The amount of subjects with detectable level of IL-8 was 40% in Group B1 vs. 12.5% in Group B2 and 50% in Group K1 vs. 4.5% in Group K2 (p < 0.02). In conclusion, our study showed that increased level of IL-6 in elderly seems to reflect the diseases rather than aging itself.