10. AIHA Flashcards
the first clue to an autoAb
DAT+ with plasma Abs reactive with ALL cells tested
important to obtain patient’s … (3) in autoAb investigation
- diagnosis
- transfusion hx
- medications
clinical s/s that point to AIHA (6)
- Normocytic or macrocytic anemia
- Reticulocytosis
- ↓ haptoglobin
- ↑ lactate dehydrogenase
- ↑ bilirubin
- DAT+
cold AIHA often associated with… (4)
- Pneumonia (Mycoplasma pneumoniae)
- Anemia
- Lymphoma
- Viral infection
DAT+ specificity
trxn
IgG with specific Ab
DAT+ specificity
WAIHA
IgG and/or C3
DAT+ specificity
CAIHA
C3
DAT+ specificity
drug interaction
IgG
serum may be nonreactive
DAT+ specificity
Clot tube stored at 4°
C3
no serum Ab
DAT+ specificity
HDFN
IgG
ABO or alloAb from mom
CAIHA phase of rxn
IS
strong reactions may carry over to AHG
may cause an ABO discrepancy
cold autoAb
IgM found in normal healthy individuals against I or H antigens
benign cold auto Ab
anti-I more common
benign cold auto titers
<64 at 4°
benign cold max temp
RT
benigns autos are NR with…
I= (cord and adult i) cells at RT
anti-H most common in —– type people
A1 type
least amount of H antigen present
occasional clinical manifestation of high-titer anti-HI benign cold autos
group O cells will have decreased red cell survival after transfusion
O cells have the most H antigen
3 pathologic cold autoAb conditions
- CAIHA
- Cold Agglutinin Syndrome (CAS)
- Paroxysmal Cold Hemoglobinuria (PCH)
characterized by agglutination, at room temp, of red cells in an EDTA specimen
CAS
CAS etiology
underlying disorder
infection (eg, Mycoplasma pneumoniae or Epstein-Barr virus)
autoimmune disorder
lymphoid malignancy
CAS type of anemia
extravascular
investigation of CAS is difficult because agglutinins are active at refrigerator temp
how do we cirumvent?
The blood tubes need to be prewarmed and samples must be transported at 37C.
CAS resolution
usually self-limiting when underlying condition is resolved
—- anti-H is CS (Bombay)
allo
CAS
DAT
eluate
titer
specificity
C3 only
eluate NR
>1000 at 4°
anti-I
treatment for severe CAS cases targets…
C1
PCH population
children
acute transient condition secondary to infection
biphasic hemolysin
definition
PCH IgG
binding to RBCs occurs at low temps, but hemolysis does not occur until C3-coated cells are warmed to 37°
affects the extremities
PCH
diagnostic test for PCH
Donath-Landsteiner test
PCH
DAT
eluate
IAT
specificity
DAT+ with C3 only
eluate NR
IAT=
anti-P
PCH sx
anemia, frequently marked
hemoglobinurea
resolve ABO discrepancy once cold autoAb is IDd
prewarm technique
steps of prewarm technique
- incubate plasma and reagent cells at 37° for 15 min
- two drops plasma added to reagent cells
- incubate for 30 mins w/o potentiator
- if AHG, warm saline must be used for wash
methods to eliminate cold autoAb after ID
sulfhydryl reagents (DTT and 2-ME) denature IgM pentamer
rarely used to resolve cold autoAb
adsorption at 4°
transfusions for benign cold autoAb pts
XM compatible by prewarm
and/or
use of IgG AHG reagent
transfusions for CAS pts
transfusion should not be withheld due to serologic incompatibility
transfuse smallest volume possible
transfusions for PCH pts
randomly selected units of blood
if pt does not response adequately, use P= units
WAIHA lab findings (6)
- ↓ H&H
- ↑ MCV
- ↓ haptoglobin
- ↑ bilirubin
- ↑LDH
- reticulocytes, spherocytes, nRBCs, fragmented RBCs
polychromasia
symptom of WAIHA
bluish tint to RBCs
WAIHA etiology
secondary to disease state (Hodgkins; CLL; SLE; viral infection; immune deficiencies; GI autoimmune disease)
idiopathic
hallmark of WAIHA
DAT+
mostly IgG and C3
WAIHA with —- + are more hemolytic and harder to tx
C3d
WAIHA pts may have a +/= ——, because…
ABS
at low titer, all autoAb is adsorbed
DAT+ before ABS+
warm autoAb is detectable in plasma after…
titer rises and it spills into plasma from saturated RBCs
panagglutinin in AHG
warm autoAb
main problem warm autoAb poses to BB
panagglutinins “cover” underlying alloAb