Transcript Slayt 1

IMMUNOGENETIC TESTS
MHC = Major histocompability
complex
HLA = Human lymphocyte antigen
HLA class I: HLA-A, B and C
Present on all nucleated cells
HLA class II : HLA-DQ, DP, DR
Present on: B cells, monocytes, macrophage, dendritic
cells and on activated T cells
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Solid organ and BM transplantation
Disease association
Appropiate specimens: WB, Lymphocytes,
biopsy specimens, buccal swabs, etc.
Laboratory methods
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HLA typing is performed at various
resolution levels and the methods used
also vary according to the resolution
level.
Detection at Ag level low resolution
Detection at allel level  High resolution
Anti-HLA antibodies
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Tests for the present of circulating
anti-HLA are critical for:
Organ transplants
Blood and platelet transfusions
Blood and plasma donors
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Anti-HLA antibodies in patient's serum may react with cells
from a few or many individuals.
Sensitization is reported as the percent Panel Reactive
Antibody (PRA)
Computerized analyses of lymphocytotoxicity reaction
patterns on well-characterized cell panels identify the
specific HLA-antigens against which antibodies are
directed, and "safe" antigens, which are not recognized.
Autoimmune diseases, particular medications, or
infections may cause false positive reactions.
Microwells or beads coated with HLA Ags may also used
HLA typing methodologies
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Serological methods
Cellular methods
RFLP
Sequence Based Typing (SBT)
Sequence Specific Oligotyping (SSO)
Sequence Specific Priming (SSP)
Serologic methods
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Microlymphocytotoxicity assay (Terasaki
plates)
Cellular HLA Typing Methods
MLC (mixed lymphocyte culture)
Mytomicin C treatment  Stimulator cells
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Sequence specificprimers (SSP)
Sequence specific
oligohynridisation (SSO)
Luminex
Sequence based typing
Human MHC class I chainrelated gene A (= MICA) typing
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The expression, structure and function of MICA
differs considerably from classical HLA class I
genes.
act as ligands for cells expressing a common
activating natural killer cell receptor (NKG2D)
Highly polymorphic; functionally relevant in
transplant rejection, autoimmune disease and
cancer
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MICA antibodies have been implicated in solid
organ rejection.
MICA genotyping uses luminex technology to
type MICA alleles.
The test targets MICA sequence
polymorphisms defined by DNA-typing
methods.
MICA typing can be helpful in determining
whether patients are matched or mismatched
for MICA with their donors.
KIR typing
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Killer Cell Ig-Like Receptors (KIRs).
NK cells distinguish abnormal cells from
healthy cells through variable inhibitory and
activating KIRs.
The combinations of KIR and HLA class
molecules balance the NK cell response
between tolerance of healthy cells and killing of
unhealthy cells
16 KIR genotypes
There are 14 KIR genes and two pseudogenes located in the
leukocyte receptor complex (LRC) on chromosome 19q13.4.
Human NK cells express various combinations of these 16 KIR
genes with two common haplotypes: Group A, which has more
inhibitory receptors and Group B, which has more activating
receptors.
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Microchimerism
Testing
Sequence Based
Typing (SBT)
Sequence Specific
Oligotyping (SSO)
STR and VNTR
VNTR
Clinical Indications for Chimerism Testing in
Hematopoietic Cell Transplant
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Routine post-transplant documentation of the
donor/recipient origin of white blood cells in peripheral
blood and/or marrow. Documentation of engraftment may
include testing lineage-specific cell subsets, such as CD3
positive T-cells and CD33 positive myeloid cells.
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Evaluate donor/recipient cells in patients with inadequate
marrow function.
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Define whether recurrent or new malignancy has originated
from recipient or donor cells.
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Assess prognostic risks of rejection and recurrent
malignancy.
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Document the persistence of donor cells post-transplant in
patients with recurrent disease or prior to donor
lymphocyte infusion (DLI).
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Evaluate whether graft rejection has occurred in recipients
that are candidates for a second transplant.
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Differentiate the origin of donor cells in recipients who
have received a second transplant with a different donor or
a transplant with double cord blood units.
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Detect the presence of maternal derived cells in patients
diagnosed with Severe Combined Immuno-Deficiency
(SCID).
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Verify genetic identity of putative identical twins.