Immunology of Transplant Rejection

IMMUNOLOGY OF TRANSPLANT REJECTION

Rejection is caused largely by differences in HLA alleles between donor and recipi-ent. Immunosuppressive agents are used to prevent and mitigate rejection.

·              Hyperacute rejection occurs within minutes to hours due to preformed anti-bodies in the recipient. Lymphocyte cross-matching has almost eliminated this problem.

·              Acute rejection occurs in the first 6 months and may be cellular (CD8+ Tlymphocytes kill graft cells) or antibody-mediated.

·              Chronic rejection occurs after months or years and may be cell-mediated orantibody-mediated. The vasculature components are targeted, and the histo-pathologic changes depend on the organ involved.