<prompt> Allograft rejection is an example of?GVHDDelayed types hypersensitivityImmediate hypersensitivityAcute rejection  <response>: Ans. b Delayed type hypersensitivityRef: Robbins 9thpg 231-234; 8thpg 221-229; Refer Ans 200Types of Rejection Pathway:Direct pathway: CD4 and CD8-T cells of the transplant recipient recognize allogeneic donor MHC molecules on the surface of APCs in the graft.Indirect pathway: recipient CD4-T lymphocytes recognize MHC antigens of the graft donor after they are presented by the recipients own APCs.As both the pathways are cell mediated, hence they are delayed hypersensitivity reactions. 