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What is Secondary allograft rejection is mediated by? and explain in detail?
Secondary rejection (accelerated rejection)

After 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.