β-Interleukin I (163-171), human, an immunostimulatory fragment of human IL-1β peptide, is a T cell activator. β-Interleukin I (163-171), human is not an IL-1R-binding domain of IL-1β. β-Interleukin I (163-171), human is a potent adjuvant that enhances the immune response in a variety of exptl. situations.