Physiological significance of the interleukin 1 receptor accessory protein

Neuroimmunomodulation. 2001;9(4):225-30. doi: 10.1159/000049030.


Interleukin 1 receptor accessory protein (IL-1RAcP) is an essential signal-transducing component of the IL-1 receptor type I. The recent availability of IL-1RAcP-deficient (KO) mice allows to study the in vivo function of IL-1RAcP. Animals were injected intraperitoneally with rat recombinant IL-1beta (200 ng/mouse), lipopolysaccharide (LPS, 5 microg/mouse), or subjected to 1-hour restraint stress. Neuroendocrine and immune parameters were measured 2 h after IL-1 or LPS injection or just after restraint. In wild-type controls, IL-1 and LPS activated the hypothalamic-pituitary-adrenal axis and increased plasma IL-6. In KO mice, the plasma levels of corticosterone and IL-6 increased after LPS, but not after rat recombinant IL-1beta. The LPS-induced depression of the lymphoproliferation was similar in wild-type and KO mice. Finally, the 1-hour restraint was able to increase the plasma levels of corticosterone in KO mice. These results show that IL-1RAcP is essential for physiological activities of peripheral IL-1, as it was previously demonstrated for those of brain IL-1. However, using IL-1RAcP KO mice, we were unable to demonstrate a specific role of endogenous IL-1 during LPS-induced inflammation. Moreover, stress-induced activation of the hypothalamic-pituitary-adrenal axis may occur in the absence of the IL-1-transducing receptor, IL-1RAcP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Chemistry / drug effects
  • Concanavalin A / pharmacology
  • Corticosterone / metabolism
  • Humans
  • Hypothalamo-Hypophyseal System / drug effects
  • Hypothalamo-Hypophyseal System / physiopathology
  • Inflammation / chemically induced
  • Inflammation / physiopathology
  • Interleukin-1 / pharmacology
  • Interleukin-1 Receptor Accessory Protein
  • Interleukin-6 / metabolism
  • Lipopolysaccharides / pharmacology
  • Lipopolysaccharides / toxicity
  • Lymphocyte Activation / drug effects
  • Mice
  • Mice, Knockout
  • Pituitary-Adrenal System / drug effects
  • Pituitary-Adrenal System / physiopathology
  • Proteins / genetics
  • Proteins / physiology*
  • Rats
  • Receptors, Interleukin-1 / drug effects
  • Receptors, Interleukin-1 / physiology*
  • Recombinant Proteins / pharmacology
  • Restraint, Physical
  • Signal Transduction / drug effects
  • Stress, Physiological / etiology
  • Stress, Physiological / physiopathology


  • IL1RAP protein, human
  • Il1rap protein, mouse
  • Il1rap protein, rat
  • Interleukin-1
  • Interleukin-1 Receptor Accessory Protein
  • Interleukin-6
  • Lipopolysaccharides
  • Proteins
  • Receptors, Interleukin-1
  • Recombinant Proteins
  • Concanavalin A
  • Corticosterone