Renal transplant: HLA typing and graft failure

The human leucocyte antigen (HLA) system is the name given to the major histocompatibility complex (MHC) in humans. It is coded for on chromosome 6.

Some basic points on the HLA system

• class 1 antigens include A, B and C. Class 2 antigens include DP,DQ and DR
• when HLA matching for a renal transplant the relative importance of the HLA antigens are as follows DR > B > A

Graft survival

• 1 year = 90%, 10 years = 60% for cadaveric transplants
• 1 year = 95%, 10 years = 70% for living-donor transplants

Post-op problems

• ATN of graft
• vascular thrombosis
• urine leakage
• UTI

Hyperacute rejection (minutes to hours)

• due to pre-existing antibodies against ABO or HLA antigens
• an example of a type II hypersensitivity reaction
• leads to widespread thrombosis of graft vessels → ischaemia and necrosis of the transplanted organ
• no treatment is possible and the graft must be removed

Acute graft failure (< 6 months)

• usually due to mismatched HLA. Cell-mediated (cytotoxic T cells)