Interleukin-6 and selected plasma proteins in healthy persons of different ages.

In the present study, interleukin-6 (IL-6) and several acute phase proteins were measured in healthy participants (23-87 years of age). A linear correlation between IL-6 and age was established with an increase of 0.016 pg/ml (0.004) per year of life. Whereas CRP remained below 0.5 mg/dl in all participants, an increase with age for fibrinogen and an inverse relation for albumin as well as transferrin were obtained. However, the increase of IL-6 did not correlate with any of these changes. IL-6 associated diseases may therefore occur more often with advancing age, but in healthy participants IL-6 does not explain the changing plasma protein pattern resembling that of an acute phase reaction.