Rytvela is an all D peptide derived from an extracellular loop region of the interleukin-1 receptor accessory protein (IL-1RAcP), which acts as an allosteric negative modulator of the interleukin-1 receptor (IL-1R). In vitro, rytvela is specific, potent and effective and blocks human thymocyte proliferation with an IC50 of 1 nM, Rytvela does not significantly inhibit NF- kappa B, but instead it selectively inhibits the IL-1R downstream stress associated protein kinases/transcription factor c-jun and Rho GTPase/Rho-associated coiled coil containing protein kinase signaling pathways. In vivo rytvela is active in models of hyperthermia and inflammatory bowel disease and topically in contact dermatitis.A scrambled control peptide, rytvela scrambled peptide, is also available.