<prompt> All of the following regarding acute graft rejection are true, except:CD8 T-cells directly destroy the graftIt is the principal cause of early graft failurePreformed antibodies against graft are the main causative factorCytokines secreted by CD4 T-cells cause inflammation which destroys the graft  <response>: Hyperacute rejection is mediated by preformed antibodies specific for antigens on graft endothelial cells. Acute graft rejection: It occurs within days or weeks after transplantation and is the principal cause of early graft failure. Divided into two types: In acute cellular rejection, CD8 CTLs may directly destroy graft cells, or CD4 cells secrete cytokines and induce inflammation, which damages the graft. In acute antibody-mediated vascular, or humoral rejection, antibodies bind to vascular endothelium and activate complement the classical pathway 