Can an increased level of circulating IL-8 be a predictor of human longevity?

Interleukin-6 (IL-6) and IL-8 are considered to be potent inflammatory agents. However, IL-8 has also been reported to serve as an organ protective factor. The goal of our study was to compare the circulating levels of IL-8 and IL-6 in C-reactive protein (CRP)-negative subjects of different ages. Seventy subjects living in the Wielkopolska region were enrolled into the study and divided into three groups: group 1-30 young healthy subjects 21-37 years of age; group 2-30 healthy elderly individuals, age 65-87; group 3-10 centenarians (100-105 years). In all of these subjects, serum levels of IL-6 and IL-8 were assessed with an enzyme-linked immunosorbent assay. Concerning IL-6, both the serum concentration and the frequency of results above the sensitivity limit were comparable in all groups. With respect to IL-8, the frequency of results beyond the sensitivity limit in groups 1 and 2 did not differ significantly (5/30 and 8/30, respectively). By contrast, the majority of subjects from group 3 had an IL-8 level above the limit (9 out of 10; p