The Immunological Basis of Transplant Rejection

The immunological defense mechanism that so ably protects against invading microorganisms and cancer cells also exerts its actions on foreign cells and tissues that have been intentionally transplanted for therapeutic purposes. The process 

Antigen fragment held within peptide groove 

Except in a few isolated instances, such as when the recipient s immune system is grossly impaired or when the donor and recipient are identical twins, some degree of immunological rejection is a natural consequence of all transplantation. 

Fortunately, hyperacute rejection may be largely eliminated by cross-matching the patient s serum against the donor lymphocytes using a variation of the lymphocyte microcytotoxicity test. The patient s serum is placed in the wells of a tissue typing tray and donor lymphocytes are added. The cells are examined for lysis after an appropriate incubation period and the addition of complement. If 

Still more recent was the introduction of another immunosuppressive drug known as FK-506, which was first described in Japan in 1987 (K7, K8) and introduced for clinical use in 1989. The drug was discovered when a Streptomyces strain isolated from a soil sample from Tsukuba, Japan, was found to have powerful immunosuppressive properties (G15). Although differing considerably from CyA in structure, FK-506 acts in a similar way by inhibiting T-cell activation through interference with the production of interleukin 2 (S9). 

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