Implications for Interleukin-33 in solid organ transplantation

► IL-33 is expressed in the epithelium and vasculature of transplanted solid organs. ► Distinct domains allow IL-33 to act as a cytokine and a regulatory nuclear factor. ► IL-33 is a pleiotropic cytokine that promotes Type-1, -2 and regulatory responses. ► Data support a protective role for IL-33 following heart transplantation. ► IL-33 may contribute to poor lung or intestine transplant outcomes.