AIHA Flashcards
What are the 4 causes of a positive DAT?
- Txn rxns
- HDFN
- Autoimmune hemolytic anemias (warm and cold)
- Drugs
Transfusion reactions
- Alloimmune? Autoimmune?
Alloimmune
Transfusion reactions
- Appearance of DAT
?
HDFN
- Alloimmune? Autoimmune?
Alloimmune
HDFN
- Appearance of DAT
?
Autoimmune hemolytic anemia
- Alloimmune? Autoimmune?
Autoimmune
Autoimmune hemolytic anemia
- Appearance of DAT
Positive
- Autocontrol is positive
Drugs
- Alloimmune? Autoimmune?
?
Drugs
- Appearance of DAT
Positive (common)
Typical lab findings of a patient w/ AIHA
- Macrocytosis
- Spherocytosis
- ↑ retics, unconjugated bili, LDH
- ↓ haptoglobin
- Intravascular hemolysis may lead to hemoglobinemia and hemoglobinurea
Diagnostic test for AIHA
Positive DAT (positive AC and Rh control also)
Categories of AIHA
- Cold AIHA → CHD, M. pneumoniae, IM
- PCH
- Warm AIHA
- Drug-induced hemolytic anemia
Autoanti-I
- Who makes the autoAbs?
Everyone?
Autoanti-I
- Expected test rxns w/ adult vs. cord cells
- Reacts w/ adult cells
- Non-reactive w/ cord cells
Autoanti-H
- Who makes the autoAbs?
Seen in group A1 and A1B patients, whose cells have most of the “H” Ag
Autoanti-H
- Expected test rxns w/ adult vs. cord cells
Strongly reactive w/ group O cells and non-reactive w/ A1 or A1B
Procedure that removes Abs (usually autoAbs or Ab to high frequency Ags) from aliquot of serum in order to see if there are underlying Abs in the serum aliquot
Adsorption (DAT, elution w/ EGA/CDP treated patient cells, IAT)
Procedure for adsorption
Performed by incubating serum w/ cells having corresponding Ag under optimal conditions so Ab will attach to cells (Ag), thus removing Ab from serum upon centrifugation
- Underlying Abs will be detected upon testing eluate adsorbed serum
Interpretation of adsorption results
?
This is performed when IgG Ab is coating the cells in order to ID the Ab
Elution
Procedure for elution
Cells that are coated w/ Abs are treated (w/ acid) to disrupt bonds b/w Ag and Ab
- Abs released into supernate (eluate), which can then be tested for identification of Ab
Interpretation of eluate results
?
Demonstrates anti-P specificity and is diagnostic test used for PCH
Donath-Lndsteiner test
Procedure for Donath-Landsteiner test
2 red top (serum) tubes drawn from patient and kept at 37°C; control tube remains at 37°C; the “test tube” is incubated at 4’C and then back to 37°C, centrifuge and look for hemolysis in both tubes
Interpretation of Donath-Landsteiner test
- Pos: hemolysis
- Neg: no hemolysis
Purpose is to remove the Ab coating the cell when patient ccells can’t be AHG-Ag typed by routine methods (such as in WAIHA)
EGA or CDP treatment of patient cells
Procedure for EGA or CDP treatment of patient cells
?
Interpretation of EGA or CDP treatment of patient cells
?
?
Pre-warm testing
Procedure for pre-warm testing
?
Interpretation of pre-warm testing
?
List the 3 different types of adsorption
- Autoadsorption
- Homologous adsorption
- Differential adsorption or “triple” adsorption
Adsorption where patient can’t have been transfused in the past 3 months
Autoadsorption using patient’s own cells
Adsorption where patient has been recently transfused and therefore must use donor cells that have patient’s same phenotype
Homologous adsorption
Adsorption most common in reference labs using 3 donors w/ known phenotypes for all other blood groups
Differential adsorption or “triple” adsorption
Abs being directed against an individual’s own RBCs
AutoAbs
IgG Ab that binds to patient’s cells at cold temps, fixes C’, causes intravascular hemolysis at 37°C (IgG elutes off cells at 37°C)
Biphasic autohemolysin
?
Selective allogeneic adsorption
?
ZZAP treatment
?
Panreactive
?
Polyagglutinable
?
Least incompatible
Shortened red cell survival due to immune response (Ab production)
IHA
What is the autoAb production theory?
Autoantibody production is usually prevented by feedback mechanism. Suppressor T cells induce tolerance to “self” Ags by inhibiting B cell activity. If T-suppressor cells lose function then autoantibody production results
Appearance of positive DATs for autoAbs
?
Appearance of positive DATs for alloAbs due to txn rxns
Recipient Ab attaches to transfused donor cells w/ corresponding Ag
Appearance of alloAbs due to HDFN
Mother’s IgG Ab crosses placenta and attaches to baby’s paternally-derived Ags
Purpose is to remove the cold autoAb from serum so underlying alloAbs can be detected
Cold autoadsorption
Procedure for cold autoadsorption
Aliquots of patient’s own cells are used to remove autoantibody from patient’s serum at 4’C, leaving alloab in absorbed serum; only performed if no recent transfusions in the last 3 months; test adsorbed serum at 37°C-AHG
Effect of a positive DAT on weak D or other AHG-Ag typings
Since the patient cells are already coated w/ Ab the AHG/weak D will always be positive unless treated
AIHA is problematic for BB testing, b/c patients destroy their own cells as well as ____ cells, and all XM may be ____
Donor; incompatible
Which Rh Ab is the most common?
Anti-e
List 4 mechanisms of drug-induced IHA
- Drug independent
- Immune complex (innocent bystander)
- Drug-adsorption (Hapten)
- Membrane modification
Immune complex/innocent bystander mechanism of drug-induced IHA
- Theory
Drug binds w/ anti-drug and forms complex that accidentally “bumps” into RBCs and cause positive DAT by binding C’ onto cell
Immune complex/innocent bystander mechanism of drug-induced IHA
- What is DAT coated w/?
C’ only
Immune complex/innocent bystander mechanism of drug-induced IHA
- Eluate pattern
Non-reactive
Drug-adsorption mechanism of drug-induced IHA
- Theory
Drug binds firmly to cell membrane and anti-drug then binds drug → DAT +
Drug-adsorption mechanism of drug-induced IHA
- What is DAT coated w/?
IgG
Drug-adsorption mechanism of drug-induced IHA
- Eluate pattern
Non-reactive
Membrane modification mechanism of drug-induced IHA
- Theory
Drug and plasma proteins adsorb onto memebrane and cause positive DAT
Membrane modification mechanism of drug-induced IHA
- What is DAT coated w/?
Variable (IgA, IgM, IgG may bind C’ so DAT varies as to which component is positive)
Membrane modification mechanism of drug-induced IHA
- Eluate pattern
Non-reactive
Drug independent mechanism of drug-induced IHA
- Theory
T-suppressor cells altered causing a production of autoAbs →DAT +
Drug independent mechanism of drug-induced IHA
- What is DAT coated w/?
IgG
Drug independent mechanism of drug-induced IHA
- Eluate pattern
Panreactive (IAT +)
Hemolytic Txn Rxn (HTR)
- Ig type
IgM or IgG
HTR
- DAT + due to…
IgG and/or C’ (DAT mf)
HTR
- IAT pos/neg?
Positive for specific alloAb
HTR
- Eluate pattern
Specific alloAb
HTR
- Txn requirements
Ag negative blood
CHD
- Patient population
Eldelry or middle-aged
CHD
- Pathogenesis
Idiopathic
- Secondary to M. pneumoniae or infectious mononucleosis
CHD
- Clinical features
- Acrocyanosis
- Numbness in extremities
- Raynaud’s syndrome
- Hemogloinurea (in some)
- Autoagglutination of blood at RT
CHD
- Severity of hemolysis
Chronic and rarely severe
CHD
- Site of hemolysis
Extra/invascular
CHD
- Thermal range
High (up to 31°C)
CHD
- Titer
High ( > 1000)
CHD
- Donath-Landsteiner test
Negative
CHD
- Treatment
Keep warm/avoid the cold
- If needs txn, transfuse blood through a blood warmer
CHD
- Cause
Anti-I (very high titers and greater thermal amplitude)
CHD
- Reactivity temperature
4°C
Paroxysmal Cold Hemoglobinurea (PCH)
- Patient population
Kids and young adults
PCH
- Pathogenesis
Following infection (measles, chicken pox, flu, infectious mono)
PCH
- Clinical features
- Fever
- Shaking, chills
- Malaise
- Abdominal cramps
- Back pain
PCH
- Severity of hemolysis
Acute and rapid
PCH
- Site of hemolysis
Intravascular
PCH
- Thermal range
Moderate ( < 20°C)
PCH
- Titer
Moderate (< 64)
PCH
- Donath-Landsteiner test
Positive
PCH
- Treatment
Avoid cold exposure (supportive)
CHD
- Lab findings
- Hemoglobinurea
- High titer anti-I (?)
PCH
- Lab findings
- Hemoglobinurea
- Hemoglobinemia
CHD
- Ig type
IgM (anti-I/i)
PCH
- Ig type
IgG (anti-P, biphasic hemolysin)
CAIHA
- DAT + due to…
C’ only
CAIHA
- IAT pos/neg?
Positive
- anti-I, anti-H, anti-IH, DL Ab
CAIHA
- Eluate pattern
Nonreactive
CAIHA
- Txn requirements
Blood warmer
WAIHA
- Ig type
IgG
WAIHA
- DAT + due to…
IgG w/ or w/o C’
- Patient cells can’t be AHG-Ag typed by routine methods
- Must treat patient cells w/ EGA or Chloroquine diphosphate (CDP) to remove the Ab coating cells
WAIHA
- IAT pos/neg?
Positive or negative
- ID positive adsorption must be performed to look for underlying alloAbs
WAIHA
- Eluate pattern
Panreactive or Rh specificity
WAIHA
- Txn rxn
Least incompatible; phenotypically similar blood
Drug-induced IHA
- Txn rxn
XM compatible
WAIHA
- Treatment
- Cortosteroids
- Splenectomy
- Immunosuppressive drugs
- Txn as a last resort
Drug-induced IHA
- Treatment
Discontinue drug
WAIHA
- What temperature does it react?
37°C
WAIHA
- Majority of patients will have ____ and need ____
Anemia; txns
WAIHA
- Symptoms
Pallor, weakness, dizziness, dyspnea, jaundice, unexplained fever
WAIHA
- Onset is usually ____
Chronic
WAIHA
- The MOST important part of a workup is ____
To identify any underlying alloAbs
- Adsorption procedures often needed
WAIHA will have ____ autocontrol,
WAIHA will have ____ autocontrol
Positive; negative
WAIHA is ____ w/ ficin/PEG/gell than LISS; HTLA are ____ w/ the media
Enhanced; variable
WAIHA is ____ w/ all cells; HTLAs are ____ if tested against Ag negative cells
Positive; negative
Which adsorption technique would you recommend for an untransfused patient diagnosed w/ WAIHA and whose RBCs are coated w/ Ab (DAT +)?
Autoadsorption
Describe the process of autoadsorption
- Separate cells from serum so cells can be treated
- ZZAP treat patient cell s(removes Ab coating cells and enhances binding sites)
- Wash ZZAP completely and leave packed cell aliquotes w/ no saline in them
- Add an aliquot of patient’s serum to ZZAP-treated patient cells in ratio 1:1
- Incubate 30 min @ 37°C → spin → remove supernate and put on next aliquot of ZZAP-treated cells
- Repeat steps 4 and 5 for all aliquots (max of 4x)
- Test supernate adsorbed serum w/ panel of selected cells to ID underlying alloAbs
It’s generally NOT possible to find compatible RBCs for WAIHA patients, but if the clinican determines that the patient’s hgb does indicate the need for txn, what is the procedss for selection of RBCs in this situation?
- Phenotype patient (may need to EGA and cell separate) for Rh and K Ags
- Provide donor cells that are Ag negative for any Rh or K-Ag that patient is negative for
- Perform full XM on Rh/K-negative donor cells → incompatible @ AHG
- Transfuse patient w/ least compatible blood → must have Dr’s consent to give least compatible
