8/9/2019 5. Leukocyte Antigens

1/12

Human Leukocyte Antigen a specializedbranch or division of immunology for human

histocompatibility testing.

8/9/2019 5. Leukocyte Antigens

2/12

HistoryPatients who have been previously transfused

have alloantibodies

Alloantibodies were directed againstalloantigens not present in recipient

MAC initials of the three volunteers

Implicated in FNHTR

Advent of HLA typingGenetics was elucidated HLA antigens were

coded by two closely linked loci, each codingfor multiple number of alleles

8/9/2019 5. Leukocyte Antigens

3/12

Nomenclatur

e & Genetics

Chromosome 6

http://upload.wikimedia.org/wikipedia/en/4/4f/HLA_complex1.JPG

8/9/2019 5. Leukocyte Antigens

4/12

Nomenclatur

e & Genetics

Haplotype from each parent

8/9/2019 5. Leukocyte Antigens

5/12

Nomenclature & GeneticsPolymorphic

HLA genetic region

Determines major histocompatibility factors Recognition and elimination of foreign tissues

Also known as the MHC region

35 to 40 genes physically grouped in three

regions located on the short arm ofchromosome 6

Related genes: Glyoxalase-1 (GLO) andphosphoglucomutase-3 (PGM-3) are also linked

8/9/2019 5. Leukocyte Antigens

6/12

Nomenclature & GeneticsClass I region gene classic transplantation

molecules

HLA-A

HLA-B

HLA-C

HLA-E, HLA-F and HLA-G (non-classic)

8/9/2019 5. Leukocyte Antigens

7/12

Nomenclature & GeneticsClass II region gene

HLA-DR

HLA-DPHLA-DQ

Class III regionC2 and C4, Bf (complement factors)

21-hydroxylaseTumor necrosis factor

8/9/2019 5. Leukocyte Antigens

8/12

DetectionMolecular techniques

Serologic techniques

8/9/2019 5. Leukocyte Antigens

9/12

SignificanceSELF vs NON-SELF

Pre-transfusion and transplantation

Platelet refractory therapy and randomplatelet donors

Disease correlation

Paternity testing

Anthropologic studies

8/9/2019 5. Leukocyte Antigens

10/12

SignificanceUpon transfusion of

blood to someone who isnot genetically identical

(different HLA types):Transfused lymphocytes

mount an immuneresponse

Recipient with normal

immune systemcounterattacks

8/9/2019 5. Leukocyte Antigens

11/12

SignificanceUpon transfusion of

lymphocytes withsimilar HLA:

Transfusedlymphocytes seessimilarity & doesntattack

Recipient seesdifference in HLA &clears away foreigncells

8/9/2019 5. Leukocyte Antigens

12/12

SignificanceUpon transfusion of

lymphocytes withsimilar HLA:

Transfusedlymphocytes seesdifference & attacks

Recipient sees

similarity in HLA &does not respond

EVEN IF HOST IS IM-COMPETENT