<prompt> Secondary allograft rejection is mediated by?Memory cellsAntibodiesImmune complexesNone of the above  <response>: Secondary rejection accelerated rejectionAfter hyperacute rejection, transplantation of a second graft, which shares a significant number of antigenic determinants with the first one, results in a rapid 2-5 days rejection. It is due to the presence of T lymphocytes sensitized during the first graft rejection memory cells. Accelerated rejection is mediated by immediate production of lymphokines, activation of monocytes and macrophages, and induction of cytotoxic lymphocytes. 