Unit 5 Flashcards
What is HLA
human leukocyte antigen
polymorphic glycoproteins on surface of cells
What chromosome contains the human MHC
p arm / short arm of chromosome 6
Match Class I, class II and class III with their ___
DP, DR,DQ glycoproteins
A, B, C glycoproteins
complement and TNF
D- class II
ABC- class I
complement- class III
regions on chromosome 6 that contain genes for MHC (LOCI)
What are the 4 fields in HLA nomenclature
1- protein/ allele group
2- specific allele variants
3- synonymous DNA substitutions/ silent mutations and exons
4- non-coding regions- introns and UTRs
Are there more HLA class I genes or class II
class I- more than 20,000
class II- less than 7000
What type of inheritance do HLA genes tend to have
codominant
one haplotype from mom
one haplotype from dad
What is linkage disequilibrium and does it occur in HLA inheritance
when haplotypes occur at unexpected frequencies, yes it does
deviates from the hardy winburg principle
Name what class the following genes are from?
A1
B8
DR17
A1 and B8 class I
DR17 class II
What are the parts of the HLA class I protein
3 alpha chains and 1 B2 macroglobulin
2 alpha and 2 beta chains
What kind of cells have an HLA class I? and HLA class II?
all nucleated cells
antigen presenting cells
What is the source of antigens being screened by HLA class I?
And class II?
endogenous
exogenous
What part of the Ig chain does HLA class I code for?
and class II?
both for heavy chains of class I or II glycoproteins
When does a patient need HLA typing and abs
if they are getting a solid organ transplant, BM transplant, graft transplants
What is an allogenic BM? and an auto
when a pt receives BM from someone else
auto- when a pt receives their own
BM back
What elements must match for a BM transplant to be compatible
pt HLA abs must match donor lymphsq
How is HLA tested for transfusions with the CDC method
complement deficiency cytotoxicity assays are done to test pt serum against donor lymphs and reagent complement to see if compliment activates. AHG is also added as enhancement
How is flow cytometry used to test HLA
donor lymphs isolated by T and B cells, incubated with pt serum, if HLA is present it will react toward the pt lymphs
What is engraftment monitoring and how does it work
monitors signs of GvHD
identifies short tandom repeats STRs between donor and pt
practice slide 26`
slide 26
What do each of these terms mean
autologous
syngenic
allogenic
xenogenix
GvHD
HvGD
syn-twin donation
xeno-other species
What cells and what class can leav to GvHD and HvGD
T cells- class I
ab responses- class II
NK- class I
compliment
Which is worse, GvHD or HvGdg
GvHD
What kind of recognition do each of these cells do
T cell
Ab
NK
T cell- direct
Ab indirect
NK allorecognition
What cells mediate HvGD in hyper acute, acute or chronic phases
hyper acute- preexisting Abs - min to hours- complement activated
acute- CD4 and CD8 - 2 weeks to 1 month
chronic- CD4 and B cell responses
What might cause a hyper acute HvGD
previous transplants or transfusions, multiple pregnancies
What are the effects of acute HvGD
vascular damage due to leukocytes attack
inflammation
tissue necrosis
ab mediated respons
What can cause GvHD
BM, thymus, spleen, blood transfusion in neonate
What are the effects of acute GvHD
endothelial tissue damage, death to skin, liver, gastrointestinal tract
rash, jaundice
What cells are activated in acute GvHD
mature T cells in the graft
What are the effects of chronic GvHD
gradual ab and slow rejection
organ damage, scar formation on organs, fibrosis and atrophy of organ
How is GvHD treated? How to prevent it?
immunosuppression and steroids
HLA testing prior to transplant
Describe the parts of direct allo recognition? and indirect?
direct-patient T helper CD4 attaches to MHC class II on donor APC, acute
indirect- donor cell proteins are presented by APCs of recipient- chronic
How is HLA used for paternity testing
HLA genes from mom and dad are used to see if child matches these
What genetic markers are analyzed in paternity testing
RBC, HLA, enzymes, proteins
What are 1st and 2nd order exclusions
1st- gene in child that is not in mom nor dad
2nd- gene not in child that is in dad
practice slide 44, 46
slide 44
first order or 2nd
What does hydrops fetalis mean
edema in fetus
What does icterus gravis mean
jaundice
What does erythroblastosis fetalis mean
immature RBCs in circulation- related to anemia
What causes the most severe form of HDFN? and the least severe
Rh system
ABO
What are the 3 main causes of HDFN
Rh, ABO, other
What are the 4 conditions that must be met for HDFN to occur
Mom is exposed to foreign antigen from pregnancy
exposed to foreign antigens causing ab production
Ab can cross the placenta (IgG)
infant must have a well developed antigen that mom doesn’t have
What is the function of placenta
O2 exchange, nutrients, waste products
barrier between mom and fetus circulation
Describe fetal blood flow
fetal veins bring oxygenated blood to heart, pumps deoxygenated blood back to placenta via arteries
maternal blood provides nutrients and removes waste
Which HDFN can occur in the first pregnancy as mild
ABO
Which HDFN does not affect the 1st pregnancy, but the second pregnancy can have severe issues
Rh
How can HDFN lead to jaundice, what is this condition called
plasma albumin binds to some bilirubin
if there is too much it will remain unbound, accumulates in CNS
kernicterus
Describe the bilirubin pathway
RBCs lyse and release heme
heme is converted into unconjugated bilirubin
free bilirubin in the bloodstream
albumin conjugates bilirubin in liver,
broken down into urobilinogen in gut
can be excreted in feces or urine
What Rh type of HDFN is most severe
anti-D most common
What antigens cant cause HDFN and why
Lewis, I and P,not well established at birth
What DAT results are expected in ABO HDFN, what other lab results can be expected
weak positive or negative
high ESR
high osmotic fragility
high spherocytes
mild to high bilirubin
What is included in prenatal testing
ABO RH type, weak D, ab screen
if Rh neg, need testing of rhogam
if ab preset, must do panel
What is ab titration
serial dilution of abs to find what dilution abs are present
How many ab titrations are preformed
3- second usually done weeks later, and ran parallel with the third
if change is more than 10 this is significant
practice slide 20 HDFN chapter
slide 20
What titers are clinically significant
16-32 or higher
What does the liley graph tell us
bilirubin test, change in A450
High billirubin means ___ RBC destruction
high
What do the zones of Liley graphs mean
1- baby is ok
2- baby affected, must monitor
3- life threatening anemia
What is cordocentesis
percutaneous umbilical blood sample
need in umbilical cord while baby still in womb
used to measure, Hgb, hematocrit, bilirubin, retics
What can be done if HDFN is occuring
deliver baby early, intrauterine exchange, docs call
What are the BB requirements for IUT
fresh blood- 5 days
CMV neg
Hgb S neg
irradiated
O neg RBCs and AB FFP
sometimes C, E and K neg
When is cord blood testing necessary
Rh neg mom
O mom
NICU
mom has ab
no prenatal history
What testing needs to be done if Weak D test is pos
elution
What can interfere with cord blood testing
wharton’s Jelly
monoclonal reagents
blocking- mom anti-D blocks binding sites on baby D cells, doesnt let reagents bind to it
What are the normal ranges for cord Hgb, and anemia
Hgb- 14-20
mild anemia- 13
moderate anemia 8-12
severe anemia <8
What bilirubin levels are bad for a fetus
4-7, too high
What is bilirubin is 16?
and if its 18-20?
16- fetal IUT needed
18- kernicterus, need labor induction
If a DAT in cord blood is pos
acid elution, test supernatant for abs
What treatments for neonatal HDFN
phototherapy for jaundice
transfusion
exchange transfusion
How to give blood products to neonate
go off of baby blood type
O best choice, AB FFL
How to give blood products to neonate
go off of baby blood type
O best choice, AB FFP
What is rhogam
fake anti-D so that mom doesn’t make her own
What kind of immunity is rhogam doing?
passive
What are the conditions to be a candidate for rhogam
rh neg mom
weak D neg mom
mom has not made anti-D yet
Rh neg mom with Rh pos baby
invasive procedure- miscarriage, abortion, ectopic pregnancy, amniocentesis
How long is Rhogam detectible in moms blood after administration
5 months
How much is each dose of rhogam
300ug
How much fetal blood will each dose of rhogam protect against
30mL of whole blood or 15mL of RBCs
What is massive fetomaternal hemorrhage
if tauma causes 30mL of fetal blood to enter moms circulation
need rosette test
What is the purpose of a fetal screen
looks for Rh pos cells from fetus in mom
What is the purpose of a fetal screen
looks for Rh pos cells from fetus in mom
pos if rosettes are found
What is the purpose of the Kleihauer Betke test?
quantitates how much fetal blood is in moms circulation
What is used to differ fetal hgb from adult hgb in KB test
acid elution- fetal hgb is resistant to it
What cells are adult and what cells are fetal in KB test
Adult- ghost
fetal- hot pink
If KB test reveals 40 cells of fetal blood, how much rhogam must be transmitted
40/ 2000= 0.02 fetal index
0.02 x 5000 = 100
100/30 = 3.3
3+1 = 4
round up +1
What are the 3 categories of immune hemolytic anemia
alloimmune- foreign
autoimmune- warm or cold ab
drug induced- damage to pt RBCs by drug
Immune hemolytic anemia lab results
hgb
hct
retic
bilirubin
haptoglobin
LDH
RBC morphology
hgb low
hct low
retic high
bilirubin high
haptoglobin low
LDH high
polychromasia, spherocytosis, NRBCs, hemoglobinemia, hemoglobinuria
What type of hemolysis causes sperocytes
extravascular
auto antibodies tend to have
panagglutination
What is the most common immune hemolytic anemia and what Ig causes it
Warm autoimmune hemolytic anemia,
IgG 70%
How does Warm AIHA affect ABO and Rh results
what are the results for DAT
AB screen
ABID
unaffected
strongly positive
positive
all tested cells are pos - panagglutination
What is the most common autoantibody
anti little e
What is the most common autoantibody
anti little e
pt is e positive
What is an elution ? What makes it positive
when you wash red cells and test the plasma for IgG
will be negative with compliment
If a pt has warm autoimmune hemolytic anemia due to C3 what will the results for an elution be?
negative
the last wash of an elution should be ___
negative
What are the treatments for warm AIHA
steroids
treat underlying condition
splenectomy
immunosuppressants
What is a warm autoabsorption
absorbs out the ab at 37C with ZZAP or PEG
remove serum, mix enhancement with RBCs allow abs to be absorbed, repeat, put plasma back into mix, add ZZAP to destroy abs
continue until auto control is neg
What are the cold abs
LIPMAN
What ab mostly causes cold hemolytic disease
anti- I
What can a cold ab do to the typing results
false positive in forward type
What results will an eluate show if there is a cold ab
negative
What ab is associated with infectious mononucleosis
anti-i
What DAT results can be expected from a cold hemagglutinin disease
+ if polyspecific
- for IgG and - C3
What treatment is used in cold hemagglutinin disease
plasma exchange
rapid erythrocyte stroma treatment- rabbit plasma
How does REST help in cold hemagglutinin disease
removes anti-I from the serum
What pts tend to get paroxysmal cold hemoglobinuria
children mostly
after viral diseases like mono, measles, mumps
What is the Donath Landsteiner test for
to looks for paroxysmal cold hemoglobinuria
exposes sample to low temps- allowing C to bind then warms them back up
What causes Paroxysmal cold hemoglobinuria
compliment binds to IgG abs
What ab is in question with Paroxysmal cold hemoglobinuria?
auto Anti -P
Why can drugs cause induced hemolytic anemia
abs react against the drug or against the RBC antigens if enhanced by drug
What DAT results are expected in drug induced hemolytic anemia
positive DAT
What are the 4 mechanisms of action that cause drug induced hemolytic anemia
drug adsorption
immune complex
membrane modification
unknown
What is the drug that most often causes drug induced hemolytic anemia through adsorption
penicillin
cephalosporin, erythromycin tetracycline
What eluate results can be expected in Drug induced hemolytic anemia drug adsorption
negative, unless tested against drug coated RBCs
What type of hemolysis occurs in drug induced hemolytic anemia through drug adsorption
extravascular
What DAT results are expected from Drug induced hemolytic anemia through adsorption
pos- polyspecific
pos- IgG
neg- C3
What is the best way to treat drug induced HA through drug adsorption
take the pt off the drug, usually ends in full recovery
What causes drug induced hemolytic anemia through an immune complex
drugs adsorbed onto RBC surface
drug and abs form a complex
complement activates
What type of hemolysis occurs in drug induced hemolytic anemia, through an immune complex
intravascular
What are the expected DAT results for drug induced hemolytic anemia by formation of immune complex
DAT polyspecific- pos
DAT IgG- neg
DAT C3-pos
What are the expected eluate results for drug induced hemolytic anemia by formation of immune complex
negative, only compliment is present not IgG
What treatment can be used in drug induced hemolytic anemia, immune complex
stop drug,
steroids, sometimes
What drugs cause DIHA through unknown mechanisms
aldomet, L DOPA, ibuprofen
What are the expected DAT results in DIHA through unknown mechanisms
pos
with everything
What are the expected eluate results in DIHA through unknown mechanisms
positive
negative in absence of drug
What antigens have weak expression at birth
Lewis
P
Lutheran
