Pre-HSCT Donor & Patient Tests.HLA Typing
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Transcript Pre-HSCT Donor & Patient Tests.HLA Typing
Pre-HSCT Donor & Patient Investigations: HLA Typing
BBMT Society of Nigeria. 15-27 July 2013
Pre-HSCT Donor & Patient
Investigation: HLA Typing
Anthony Oyekunle
Senior. Lecturer & Consultant Haematologist
Obafemi Awolowo University, Ile-Ife
Pre-HSCT Donor & Patient Investigations: HLA
Typing
Transplant Immunology
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Histocompatibility depends on MHC genes (HLA)
12 MHC genes on 6p; 3.6Mb
HLA I: α-chain (with 3 domains) + β²-microglobulin
(Chromosome 15)
Most polymorphic loci of human genome; 2584 alleles
Phenotypes fewer; fewer still detectable by serology
Usually inherited “en bloc“ → HLA haplotypes
ABDR match (familial) equivalent to genotypic identity (12/12)
Recombination events are rare; 1-2% HLA-A/B & -B/DRB1
α1 & α2 domains form peptide-binding site
HLA + 8-10aa from antigen bind TCR on CD8+ CTL
HLA II: α + β-chain; 2 domains each
APCs: dendritic, B-cells, activated T-cells & macrophages
HLA + 10-30aa from antigen bind TCR on CD4+ TH-cells
Dr A A Oyekunle
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Schematic representation of the 12 HLA loci in the MHC region that comprise more than
200 genes on 6p. The corresponding serologic antigens & alleles defined by DNA
sequences are also shown
Dr A A Oyekunle
Culled from Hematopoietic Stem Cell Transplantation; ESH-EBMT (Tiercy 2008).
Pre-HSCT Donor & Patient Investigations: HLA
Typing
Methods for HLA Typing
Low-resolution, viable lymphocytes, cross-reactivity
Cellular typing
Stem Cell Transplant Centre, Benin 15-27 July 2013
Serology: simple, low-cost, commercial trays, for HLA-A & B
BBMT Society of Nigeria: HSCT Workshop
CTLpf & HTLp assays; in-vitro, mismatch are “no vetoes“
Mixed lymphocyte culture (MLC); >25% pos → class II disparity
Role as final cellular crossmatch; if several matches found
DNA typing: PCR, HLA gene segments, nucleotide sequence
Dr A A Oyekunle
High-tech, expensive
Routine for both classes I & II; in most HLA labs
Presently available in Nigeria at
Tissue Typing Lab, OAUTHC, Ife.
Safety Molecular Pathology Lab, Enugu.
Pre-HSCT Donor & Patient Investigations: HLA
Typing
Serological Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Complement
antibody
Positive reaction to antibody
kills cells. Dead cells pick up dye.
Buffy coat
from patient
Negative reaction to antibody:
cells survive and exclude dye.
Antigens are defined using complement-dependent
lymphocytotoxicity assay & a panel of HLA-alloantisera
HLA allo-Ag typically express multiple epitopes
Public specificities are common to several antigens
E.g. A19 shared by A29, A30, A31, A32, A33 & A74
This defines crossreactive groups (CREGs) of antigens
Private specificities are unique to a single antigen
Dr A A Oyekunle
Pre-HSCT Donor & Patient Investigations: HLA
Typing
Serological Typing
Percent dead cells Score Interpretation
0 -10%
11 - 20%
21 - 50%
51 - 80%
81 - 100%
Dr A A Oyekunle
1
2
4
6
8
0
negative
possibly negative
weakly positive
positive
strongly positive
not interpretable
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Cells are examined under a phasecontrast fluorescent microscope:
pink cells are positive.
If ≥60% cells are stained, they are
considered positive for the HLA
antigen.
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
DNA Typing Methods: SSP & SSOP
PCR-based HLA typing
Partial sequence information allowing inference of HLA allele
DNA amplification; PCR techniques, primers, thermocycler
Locus-, group-, or allele-specific
SSP
SSP (sequence-specific primers) typing
SSOP (sequence-specific oligonucleotide probe) hybridization
Sequence-specific primer panel to detect polymorphisms at a locus
PCR product used in gel electrophoresis
HLA type assigned from pattern of presence & size of PCR products
SSOP
HLA gene amplified, blotted on membrane (forward blot)
Complimentary probes applied to membrane; hybridization
HLA type determined by pattern of hybridization
Reverse blot; PCR product applied to immobilized probe
Dr A A Oyekunle
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
SSP: Agarose Gel Electrophoresis
Dr A A Oyekunle
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
DNA Typing Methods:
Sequence-based typing (SBT)
SBT: involves the determination of the sequence of an
HLA gene locus
Provides the highest resolution HLA typing possible.
Polymorphic regions are amplified by PCR and then
sequenced
SBT involves PCR amplification of the locus eg HLA
DRB1; followed by determination of the base sequence
The sequence is then compared with the published
database of DRB1 genes sequences to assign alleles
Also allows for detection of new alleles
Can be fully automated, but not widely available
Dr A A Oyekunle
Pre-HSCT Donor & Patient Investigations: HLA
Typing
Dr A A Oyekunle
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
HLA Typing of Potential Donors
HLA Locus
Matching
Resolution of Testing
A
B
C
DRA
DRB1
DRB3, DRB4, DRB5
DQA1
DQB1
DPA1
DPB1
Recommended
Recommended
Recommended
No
Recommended
Unknown*
No
Uncertain*
No
Uncertain
Allele level
Allele level
Allele level
Allele level
*Unkno wn indicates that the effect o f matching has no t been evaluated; uncertain indicates that
studies disagree as to the impo rtance o f these lo ci in matching.
Dr A A Oyekunle
Hurley CK et al. Biol Blood Marrow Transplant 2003;9(10):610-5.11
Pre-HSCT Donor & Patient Investigations: HLA
Typing
HLA Nomenclature
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Complex and potentially confusing!
Designated to the WHO’s HLA Nomenclature Committee
Originally assigned based on phenotype analysis by serology
Dr A A Oyekunle
Pre-HSCT Donor & Patient Investigations: HLA
Typing
HLA Typing: Resolution
Low (A2 & A*02)
Intermediate (DRB1*11:02/03)
High (A*02:01 & A*02:01:01)
Dr A A Oyekunle
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
Immuno-incompatibility in Transplantation
Vector
of incompatibility
Host-vs-Graft MM: Donor alleles absent in recipient,
correlates with graft rejection
Graft-vs-Host MM: Recipient alleles absent in donor,
correlates with GvHD/GvL
Relation
Patient
Daughter
Age Sex
47 M
15 F
HLA*
Mismatch
Daughter
12
F
Mismatch
Sibling
Ad
M
Mismatch
Sibling
Ad
F
Mismatch
Sibling
Ad
F
Mismatch
Sibling
Ad
M
Mismatch
Sibling
Ad
M
Mismatch
Dr A A Oyekunle
A
3001
02,30(19)
0
30(19),33(19)
0
3001,3601
0
3601
1
3601
1
8001
1
3601
1
B
15(71),58(17)
15(71),58(17)
0
14(64),15(71)
1
5701
1
5101
2
1802
2
5701
1
5101
2
C
0302
03,07
0
03,08
0
0302
0
0302
0
0701
1
0101
1
0101
1
DRB1
0302,07
03,15
1
03,15
1
0301
1
0302
1
0301
1
0302
1
0301
2
DQB1
0201,03
02,06
1
02,06
1
0604
2
0201
1
0604,0302
1
0604
2
0604,0504
2
Remarks
2 GvH Ag mm
3 GvH Ag mm
4 GvH Ag mm
5 GvH Ag mm
6 GvH Ag mm
6 GvH Ag mm
8 GvH Ag mm
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Allo-HSCT Immunology
Stem Cell Transplant Centre, Benin 15-27 July 2013
Alloreactivity; basic fxns of Immune sys.
Special manifestations of Alloreactivity
Graft rejection
GvHD & GvL
Immune reconstitution: gradual replacement of host by donor
immune sys.
Dr A A Oyekunle
Pre-HSCT Donor & Patient Investigations: HLA
Typing
BBMT Society of Nigeria: HSCT Workshop
Stem Cell Transplant Centre, Benin 15-27 July 2013
The OAUTHC HLA Lab Team
THANK
YOU
Dr A A Oyekunle