HLA – for Data Managers
Hanne Baekgaard, MSc, RN, Mentor
Stephen Spellman Manager, Scientific
Services NMDP
How many chromosomes
do people have?
Chromosome 6
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The Family
Mum: a/b
Dad: c/d
Child 1
a/c
Child 2
a/d
Child 3
b/c
Child 4
b/d
HLA-Haplotype
Class II
Class I
DP DQ DR
BCA
DP DQ DR
BCA
E.g.:
HLA-A1,Cw7,B8,DR3,DQ2,DP1 - maternal
HLA-A2,Cw8,B8,DR5,DQ1,DP1 - paternal
HLA haplotype frequencies in
selected populations.
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What does the HLA – system do?
„ Naturally:
– Presents antigen to T-lymphocytes
– Helps distinguish self from non self
„ After
allo SCT:
– HLA mismatch cause GvHD after allo-SCT
The HLA system- testing
DNA
High resolution=allel
matching
Serology = Low
resolution
PCR probe
C B
A
Class I
DR
DP
DQ
Class II
HLA = Human leukocyte antigen
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Class I HLA Molecules
„
„
„
Co-dominantly expressed on the surface
of almost all nucleated cells (except red
cells and cells of the central nervous
system)
Heterozygous –two different molecules
for each gene are expressed ie. HLA-A2 /
A68
Homozygous –the same molecule for
each gene are expressed ie. HLA-A2 /A2
Class II HLA Molecules
„
„
Not as widely expressed as class I
molecules. Constitutively expressed on
the surface of B lymphocytes, dendritic
cells and thymic epithelial cells. Induced
expression in macrophages and
endothelial cells.
Can be heterozygous or homozygous
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Antigen-presenting
cell
Histocompatibility
molecule (class I or II)
peptide
T cell receptor
T cell: CD4+
or CD8+
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HLA Typing by Serology
„
„
„
Requires live lymphocytes (fresh blood)
Tests patient cells (surface antigens)
against serologic reagents with known
HLA specificities.
Anti-sera are mostly derived from
individuals who have been previously
sensitized to HLA antigens (some
monoclonal reagents available).
HLA Typing by Serology
Patient cell (antigen) + antibody + complement = cell death
DNA-Based Typing Methods
„ Sequence
Specific Oligonucleotide
Probing (PCR-SSOP)
„ Sequence
Specific Primers (PCR-
SSP)
„ Direct
Sequencing (SBT)
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HLA Typing
by DNA-based Techniques
„ Uses
DNA from the cell nucleus
„ Does not require live cells
„ More specific identification of HLA
type
„ Variety of methods are used
DNA Typing Resolution
„ Low
Resolution (Serologic level)
– DRB1*01; report as *01XX
„ Intermediate Resolution
– DRB1*010101/010201; report as
*01AB
„ High Resolution (Allele Level)
– DRB1*010101; report as is
Nomenclature of HLA alleles
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Nomenclature: Indicates
HLA: the HLA region and prefix for an HLA gene
HLA-DRB1: a particular HLA locus eg. DRB1
HLA-DRB1*13: a group of alleles which encode the DR13 antigen (low
resolution, two digits)
HLA-DRB1*1301: a specific HLA allele (high resolution, four digits)
HLA-DRB1*1301N: a null allele
HLA-DRB1*130102: an allele which differs by a synonymous mutation
HLA-DRB1*13010102: an allele which contains a mutation outside the
coding region
HLA-DRB1*13010102N: a null allele which contains a mutation outside
the coding region
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HLA-A
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HLA-A
A*01010101
A*01010102N
A*010102
A*010103
A*0102
A*0103
A*0104N
A*0106
A*0107
…. And many more…over 250
A Matched Sibling?
Mum:
Dad:
Patient
Sister
a = A2; B39; DR1
b = A1; B8; DR3
c = A32; B27; Cw2; DR 12
d = A2; B44; DR6
a = A2; B39; DR1
c = A32; B27; Cw2; DR 12
a = A2; B39; DR1
c = A32; B27; Cw2; DR 12
Can you use a parent?
Mum:
a=A*0201;B*0902;Cw*0303;DRB1*0101;DQB1*0202
b = A*0203;B*0803;Cw*0303;DRB1*0202; DQB1*0202
Dad:
c = A*0201;B*0901;Cw*0303;DRB1*0202:DQB1*0202
d = A*0202; B*0401;Cw*0303;DRB1*0603; DQB1*0202
Patient:
a = A*0201; B*0902;Cw*0303; DRB1*0101;DQB1*0202
c = A*0201; B*0901; Cw*0303; DRB1*0201;DQB1*0202
*=allele
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Unrelated donor
Patient
a = A*0201; B*0902; Cw*0101;DRB1*0101;DQB1*0202
b = A*0201; B*0901; Cw*0101;DRB1*0202;DQB1*0202
Donor 1
a = A*0204; B*0908; Cw*0101;DRB1*0103;DQB1*0202
b = A*0202; B*0905; Cw*0101;DRB1*0203;DQB1*0202
Donor 2
a = A*0201; B*0902; Cw*0101 DRB1*0101;DQB1*0202
b = A*0201; B*0901; Cw*0101 DRB1*0202;DQB1*0202
Effect of HLA on engraftment
Effect of HLA on acute GvHD
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Probability of grade III-IV aGvHD in DRB1
matched and mismatched groups.
1 year probability of survival in DRB1
matched and mismatched groups.
NMDP Allele Codes
Developed to facilitate reporting multiple
possible alleles (intermediate resolution)
„ Provides maximum information to the
NMDP network
„ Allele code lists are updated
periodically. Several file formats can be
viewed or downloaded from the NMDP
web site (www.NMDPResearch.org)
Alphabetic List Numeric List Allele Code
Tool
„
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Antigens defined by serology
typing (NMDP form)
HLA by DNA technology
(NMDP form)
Donor match (CIBMTR form)
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Antigens defined by serologic
typing (CIBMTR form)
Antigens defined by DNA
technology (CIBMTR form)
CIBMTR form
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