Non-clinical sciences/Immunology · Transplant & HLA

HLA / MHC

What it means

MHC class I (HLA-A,B,C) on all nucleated cells → present to CD8 T-cells. MHC class II (HLA-DR,DQ,DP) on antigen-presenting cells → present to CD4. Solid-organ matching prioritises DR>B>A. Disease links: HLA-B27 ankylosing spondylitis/reactive arthritis; DR3/DR4 T1DM; DQ2/DQ8 coeliac; **B*57:01 abacavir hypersensitivity; B*15:02** carbamazepine SJS.

Worked example

Test HLA-B*57:01 before abacavir to avoid a severe hypersensitivity reaction (pharmacogenomics).

In the exam

A cell-surface molecule on all nucleated cells presents intracellular peptides to CD8 cytotoxic T-cells.

What settles it

Class I (A/B/C) → CD8; class II (DR/DQ/DP) → CD4. 'I to 8, II to 4' (1×8=8; 2×4=8).

Classically confused with

Transplant rejection

Source: StatPearls