Hematology: Immune Hemolytic Anemia

the inability to recognize self antigens; autoantibodies bind to patient's own red cells, causing hemolysis

autoimmune hemolytic anemia (AIHA)

anemia caused by the production of antibodies against the cells of another person

alloimmune hemolytic anemia

autoantibodies whose optimum serologic reactivity is 37C (IgG); usually associated with some other autoimmune disorder

warm autoimmune hemolytic anemia (WAIHA)

Is hemolysis intra or extravascular in WAIHA?

extravascular

autoantibodies whose optimum serologic reactivity occurs at 4C and between 25-31C (IgM)

cold autoimmune hemolytic anemia (CAIHA)

What are the 2 differences between immediate and delayed alloimmune hemolytic anemias?

immediate is associated with ABO incompatibilities

delayed is from a secondary response (previous sensitization) to transfused red cell antigens

immediate= intravascular hemolysis (within circulation)

delayed= extravascular hemolysis (liver and spleen)

What are the clinical S/S of immediate alloimmune hemolytic anemia?

fever, shaking, chills

pain at infusion site

nausea and vomitting

low back pain (kidneys)

hypotension

hemoglobinemia, hemoglobinuria

can lead to DIC

intravascular hemolysis (within circulation)

What are the lab findings of immediate alloimmune hemolytic anemia?

decreased haptoglobin

increased plasma free hemoglobin

increased bilirubin

may see *schistocytes*

What are the clinical S/S of delayed alloimmune hemolytic anemia?

slight fever

fall in hemoglobin

mild jaundice, anemia

extravascular hemolysis (liver and spleen)

What are the lab findings of delayed alloimmune hemolytic anemia?

increased bilirubin

*increased fecal and urine urobilinogen*

positive DAT

*spherocytes*

Between ABO and Rh HDN, which is more common? More severe?

ABO HDN more common

Rh HDN more severe

What is the blood type of the mother and baby for ABO HDN to occur?

group O mom with a group A or B baby

What is the blood type of the mother and baby for Rh HDN to occur?

Rh negative mom with a Rh positive baby

What are the baby's S/S from ABO HDN?

mild jaundice

What are the lab findings in a baby with ABO HDN?

negative to mild positive DAT, numerous spherocytes, increased bilirubin

What is the treatment for a baby with ABO HDN?

phototherapy, if needed

What are the baby's S/S from Rh HDN?

jaundice, anemia, hepatosplenomegaly, erythroblastosis fetalis, kernicterus, CHF

What are the lab findings of Rh HDN?

mild to severe anemia with hgb of 8-13, increased retic, increased WBC, increased NRBCs, + DAT, positive anti-D antibody in mother's serum, increase in unconjugated bilirubin in baby

What are the *treatment options* for Rh HDN?

intrauterine transfusions, maternal plasmapheresis, exchange transfusion, phototherapy

What is the prevention for Rh HDN?

Rhogam

a passive form of anti-D given during pregnancy or after delivery

Rhogam

What are the lab findings in WAIHA?

polychromasia, increased retics

spherocytes, schistocytes

increased bilirubin and urobilinogen

decreased hgb (7g/dL)

decreased haptoglobin

increased LD

DAT +

What are the treatment options for WAIHA?

treat underlying disease

transfusions

corticosteroids, immunosuppressive drugs (suppress immune response)

splenectomy

What are the 3 types of CAIHAs?

1) cold agglutinin syndrome

2) secondary CAIHAs

3) PCH

Which antibody are CAIHAs?

IgMs

What are the lab findings of CAIHAs?

increased retics

autoagglutination at 20C

polychromasia, ansio, poik

DAT +

What are the clinical S/S of CAIHA?

rarely severe

acrocyanosis of hands, feet, ears, nose

numbness of extremeties

hemoglobinuria

weakness, pallor

weight loss

jaundice

What is the treatment for CAIHAs?

avoid the cold

Secondary CAIHAs are cold autoantibodies produced secondary to infections. What is the most common infection?

respiratory infections, esp. mycoplasma infections

What antibody is associated with PCH?

Donath-Landsteiner antibody (cold IgG!)

Which antibody is Donath-Landsteiner?

anti-I

What patient population is PCH most associated with?

children with viral diseases

PCH patients will see intermittent episodes of _______________ when patient is exposed to cold, then warmed again

hemoglobinuria

What are the medications, hemolysis (intra or extra), and S/S of immune complex mechanism of drug induced AIHAs?

quinidines, sulfoamindes

intravascular hemolysis

hemoglobinuria, hemoglobinemia

drug induced AIHA where drug-ab immune complex binds to RBC or complex directly activates complement

immune complex mechanism

How can you test the immune complex mechanism of drug induced AIHA?

in vitro agglutination when patient serum + RBCs + drug are incubated together

drug induced AIHA where drug is absorbed onto red cell, antibodies attach to red cell and lyse it

drug adsorption mechanism

What are the medications and hemolysis (intra or extra) of drug adsorption mechanism of drug induced AIHAs?

antibiotics-- penicillins, cephalosporins, streptomycins

extravascular hemolysis

drug interacts with T-regulatory cells, causing them to become dysfunctional and tell B-cell lymphs to produce abnormal B-cells; from aldomet, alpha-met dopa drugs (blood pressure meds)

autoantibody formation mechanism

drug such as cephalosporin causes proteins such as complement, immunoglobulins, albumin, and fibrinogen to absorb onto RBC membrane

non-specifc protein adsorption mechanism