Transplant rejection
What it means
Hyperacute (minutes–hours): pre-formed recipient antibody (ABO/HLA) → thrombosis; prevented by cross-matching. Acute (days–months): T-cell mediated → treat with steroids/anti-thymocyte globulin. Chronic (months–years): vascular intimal fibrosis, irreversible. GvHD: donor T-cells attack host (rash, diarrhoea, deranged LFTs) — after marrow transplant or non-irradiated cellular products.
Worked example
A transplanted kidney mottles and fails on-table within minutes → hyperacute rejection from pre-formed antibody (ABO/HLA mismatch).
In the exam
Minutes after revascularisation a transplanted kidney becomes mottled and thromboses, driven by recipient antibody that was present before the graft.
What settles it
Hyperacute = pre-formed antibody (minutes); acute = T-cell (days–weeks, treatable); chronic = fibrosis (irreversible).
Classically confused with
HLA / MHC
Source: StatPearls