Human Leukocytes Antigen

What is that
- Loci of genes that encode major histocompatibility complex.
- Situated in short arm of chromosome 6.
- Class I: A, B, C, beta-2 macroglobulin (polymorf)
- Class II: DQ, DR (monomorf, typing is often not needed).
- Haplotype: links of allelles.
- For example: HLAB 57.01.00 (the more the numbers, the higher the resolution; the higher the number, the less common it is in general).

Methods
- Complement-dependent cytotoxic test (serology) identification
   - Leukocytes isolated from the patient or donor.
   - Mixed with HLA-specific antisera (commercial).
   - Adding complement.
   - Look whether the blood cells are destroyed.
- Luminex typing (low resolution) in solid organ, and genomic (high resolution) in
   - DNA isolated from the cells (preferablly leukocytes).
   - DNA amplification using PCR.
   - Seqence specific oligonucleotide (SSO).
      - low resoloution Luminex
      - using beads and algorithm.
      - 2 digits

Use
- To check the compatibility donor and recipient.
   - 1/4 chance to have donor from the brother or sister.
- Association with disease
   HLAB27: bechterew's disease, HLA DQ2 and HLA DQ8: Coeliakkies disease
- To test for drug sensitivity.
   HLAB57 in HIV patient is sensitive to abacavir but also slower progression to AIDS.