<prompt> Secondary allograft rejection is mediated byMemory cellsAntibodiesImmune complexesNone of the above  <response>: Answer- A. Memory cellsAfter hlperacute rejection, transplantation of a second gfaft, which shares a significant number of antigenic determinants with the first one, results in a rapid 2 - 5 days rejection. It is due to presence of T-lymphocyte sensitized during the first graft rejectionmemory cells. 