blood Flashcards
ABO group discrepancies
forward and reverse grouping don’t match
Anti-reagent antibody
due to dyes in anti-A or B
Preservatives in reagents
Solve by washing patient/reagent cells
B(A) phenotype
high conc of B glycosyltransferase
has weak expression of A on RBCs, anti-A antibodies produced
detected when using MHO4 anti-A monoclonal antibody
solve by using different grouing reagent
Acquired B
Group A with gut problems. bacterial remove acetyl group
some anti-B reagent binds to the non-acetyl -> weak pos
solve by using diff reagent or decrease pH
Cell problem that result in weak reaction in forward group
B(A): group B, weak A
acquired B: group A, weak (not true) B
Chimerism
cisAB
1 allele AB, 1 allele O
decrease glycosyltransferase production -> weak reaction
usually produce weak anti-B
solve by doing family studies
Chimerism
2 different population of RBCs in circulation
Cause of natural chimerism
multiple births: blood flow b/w twins of diff group
dispermy: 2 sperm, zygote fuse to one
fetal-maternal blood
natural chimerism
reaction depends on degree of chimera
solved using history
molecular methods to Id chimera
acquired chimerism
out of group transfusions
BM/SC transplant
exchange transfusion ( replace fetal cells w/ donor cells)
steps in resolving ABO discrepancies
Re-test
wash cells and re-test
Check history (age, disease state, transfusion)
discrepancies in forward or reverse
know what’s in reagents
test for specific cause
type of transplant
Autologous: own cells, disease in remission
Allogeneic: other person, cant donate own cell due to chemo ect.
Syngeneic: identical siblings
sources of HPCs
BM
PB
Cord blood
sample prep for transplant
flow for CD34 (marker for HPCs)
BM filtered to remove fat, debris
Separate buffy coat
Transplanting
recipient marrow/immune ablated
donor cell infused
ABO incompatible OK, HPCs dont express ABO antigen
ABO Major mismatch transplants
Foreign antigen of DONOR
HOST produce abys against DONOR
ABO Minor mismatch transplants
Foreign abys in DONOR
DONOR produce abys against HOST
passenger lymphocyte syndrome: donor lymphocyte infused into recipient > haemolysis
ABO Bi-directional mismatch transplants
major and minor mismatch
e.g. A recipient and B donor
Engraftment results
Early (9-30 days): inc neutrophil count
platelet @ 15+ days
RBC @ 90+ days
require support
Transfusion support in major mismatch
until abys disappear
RBC given same group as HOST
PLT given same group as DONOR
Transfusion support in minor mismatch
until abys disappear
RBC given same group as DONOR
PLT given same group as HOST
Transfusion support in bi-directional mismatch
if HOST group A, DONOR group B
RBC group O
PLT AB
Transfusion support in organ transplant (ABO compatible)
blood products leukoreduced
no need for irradiation
Transfusion support in organ transplant (ABO incompatible)
possible major mismatch
host antibodies reduced by plasmapheresis and immunosuppressed
blood product must me compatible with host and graft for life
low frequency antigen
in >10% of population
antibodies are rare, not routinely ID
easy to find blood for transfusion
high frequency antigen
in >98% population
antibodies are rare, pos for all panel cell
Diego blood group
Di(a+b-) <0.01% in most, 0.1% in south american
di(a-b+) >99% in caucasian, africans americans, less in asain and SA
Multiple antibodies
varying strength
pos against many panel cells
pattern of reaction doesn’t match just 1
neg auto control
most common antibody combination
C&D 31%
c&E 12%
Lea&Leb 12 (seen in pregnancies)
E&K 8%
anti G
