Immune Hemolytic Anemia

Terms in this set (19)

What is IHA?
Decreased rbc survival due to reaction of antibody +/- complement with RBCs
Causes of IHA?
Autoimmune
(Primary and Secondary)
Alloimmune
Secondary autoimmune IHA
B cell malignancy (CLL, NHL) - 25% of AIHA
Autoimmune disease - 12% of AIHA
Drug induced - cefotetan
Infection (Mycoplasma, EBV, other viral [PCH])
Other - inflammatory disease, solid tumor, pregnancy, BMT
Alloimmune IHA
Transfusion Reaction - Acute, Delayed
Hemolytic disease of the newborn
ABO-mismatched BMT
Pathogenesis of Autoimmunity to RBC?
Loss of immune tolerance to "self" antigen
Infection-induced auto-Ab
Drug-induced auto-Ab (more later)
Lab features of AIHA?
Blood & Marrow
Anemia - (normocytic or macrocytic if ↑↑ retics; FA def.)
Reticulocytosis, up to 3-4x IF normal marrow function
Blood film - spherocytosis, polychromasia
Bone marrow - erythroid hyperplasia

Chemistry
Increased LDH, indirect (unconjugated) bilirubin
+/- Decreased Haptoglobin

Immunohematology
Positive DAT - IgG +/- C'
Positive IAT - (sometimes negative - why?)
Antibody specificity - panreactive; frequently Rh "core"
What is the most common and serious HTR due to?
ABO blood mismatch- Fever back pain, Hemoglobinemia/uria, shock, renal failure, DIC...
Hemolytic disease of the newborn
Most severe- anti-D
Mot common- ABO

Anti-D due to a sensitized mother who is anti D after exposed to D antigens
For Hemolytic Disease of the Newborn, what happens to the newborn and what is the prevention?
Newborn- Incrase indirect bilirubin- kernicterus
Prevention- RhIg prevents anti-D sensitization
Name two tests to diagnose IHA?
Direct Antiglobulin Test- always positive
Indirect Antiglobulin Test- pos or neg
Antoglobulin (coombs test)
Purpose:
To detect immune reactions to RBC

Types:
Direct - Are pt's RBC coated with IgG or C'?

Indirect - Does pt's PLASMA contain an antibody that reacts with "reagent" rbc? (type O)
If there is IgG or C* on RBC what does that mean?
+Direct Antiglobulin Test
True or False- a +DAT always indicates rbc hemolysis?
FALSE
What does IAT answer?
Does the pt's PLASMA contain an unexpected antibody to rbc2?
IgG antibody to "Reagent" RBC in patient's plasma / serum
+ Indirect Antiglobulin Test
Cold Antibody AIHA lab features?
Hemolytic anemia - normo/macrocytic
↑retics, LDH; ind. Bili.; ↓ Haptoglobin
+/- Intravascular hemolysis - ↑ plasma Hb, Hburia, hemosiderinuria, etc
Positive DAT & IAT with anti-C' (due to IgM)
High titer cold agglutinin (~ 1:1000)
Antibody specificity:
Mycoplasma, EBV - anti-I (or i)
Primary or Lymphoma - monoclonal anti-I
PCH (post-viral) - anti-P (Donath-Landsteiner IgG)
+/- Underlying disease, eg infection, lymphoma
Drug-related AIHA clinical features?
Onset of anemia within days, weeks, or months after drug administration

Anemia may develop slowly to explosively

Anemia responds to discontinuation of drug within days to weeks, to months
For Drug-Related AIHA, is the hemolytic anemia intravascular or extravascualr or both, is the DAT Negative or Positive and is the IAT positive or Negative?
may be intravascular or extravascular

DAT is Positive
may be with either IgG or C' or both

IAT may be positive or negative
Drug in test mixture through all wash steps is necessary to demonstrate +IAT for "ternary" and hapten type. IAT is usually negative for "protein absorption" type.
Current major cause of Drug related AIHA?
2nd - 3rd generation cephalosporins are the current major causes of severe/fatal drug-related AIHA
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