Effects of acute stress, relaxation, and a neurogenic inflammatory stimulus on interleukin-6 in humans.

Effects of three experimental manipulations: mental stress, relaxation, and a nociceptive inflammatory stimulus, capsaicin, on levels of interleukin-6 (IL-6) were examined. Fifty subjects were pre-trained in relaxation and then randomized to a stress (Stroop test), relaxation (tape), or control (video) manipulation. Subjects participated in an evening reactivity session including 20 min of stress, relaxation, or control followed by a capsaicin injection in the forearm. Cardiovascular variables and levels of IL-6 were measured before and after the manipulation, and at regular intervals up to 60 min post-capsaicin. Group assignment did not differentially affect change in IL-6 over time, either before or after capsaicin. Small but significant increases in IL-6 were seen at 60 min post-capsaicin. These findings suggest that an acute stress manipulation does not modulate IL-6 within this time frame. Although IL-6 did increase following a neurogenic inflammatory stimulus, it did so subsequent to the maximum flare, suggesting that flare mechanisms are independent of IL-6.