IL17A and chronic graft versus host disease: In addition, in chronic graft-versus-host disease (GVHD), a major complication of allogenic stem cell transplantation, the KC-mediated secretion of chemokines (CXCL9 and CXCL10) leads to the recruitment of alloreactive T cells into the skin.14 These allogenic T cells predominantly belong to the IFNγ-producing Th1/Tc1 and IL-17-producing Th17/Tc17 subpopulations and cause cutaneous manifestations, e.g., follicular erythema.15–17