IL-6 enhances plasma IL-1ra, IL-10, and cortisol in humans.
Level 3 - non-randomized controlled study
Controlled human experimental study; randomization and blinding are not reported in the abstract.
PubMed 12857678 · doi:10.1152/ajpendo.00074.2003
What was done
Young healthy volunteers received a 3-hour low-dose intravenous infusion of recombinant human interleukin-6 (rhIL-6, achieving plasma levels of ~140 pg/ml, corresponding to strenuous exercise) or saline. Researchers measured circulating levels of TNF-alpha, IL-1 receptor antagonist (IL-1ra), IL-10, C-reactive protein (CRP), cortisol, epinephrine, leukocyte counts (neutrophils and lymphocytes), body temperature, mean arterial pressure, and heart rate.
What was found
Infusion of rhIL-6 achieved plasma levels of ~140 pg/ml and did not increase pro-inflammatory TNF-alpha. Compared with saline, rhIL-6 elevated anti-inflammatory cytokines IL-1ra and IL-10, and increased CRP at 3 hours post-infusion with further elevation at 16 hours. rhIL-6 also increased plasma cortisol, circulating neutrophils, and decreased lymphocyte counts, without affecting plasma epinephrine, body temperature, mean arterial pressure, or heart rate. Numerical values for cytokine and cell changes were not provided in the abstract.
Why it matters
It demonstrates that transient physiological elevations of IL-6 provoke anti-inflammatory cytokine release (IL-1ra, IL-10) and cortisol-mediated leukocyte redistribution rather than a pro-inflammatory cascade, elucidating the mechanism behind exercise-induced immune shifts.
Limits
The abstract does not disclose the sample size, sex distribution, or whether the infusion was randomized or blinded. Effects of chronic IL-6 exposure and applicability to clinical or older populations were not studied.
Cited by
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