Immune Hemolysis Flashcards
Which molecules does DAT detect?
IgG +/- C3
Warm Abs
Molecules
Site of RBC destruction
Causes
IgG +/- C3
Spleen
Caused by drugs and B lymphocyte malignancies
Cold Abs
Ig
Site of RBC destruction
Causes
IgM and C3
Liver (or intravscular)
Caused by infections and B lymphocyte malignancies
Treating warm Abs (4)
Corticosteroids, splenectomy, rituximab, transfusion
What does DAT show for cold agglutinin syndrome?
Positive for C3, neg for IgG
Treatment for Cold agglutinin syndrome (4)
- Corticosteroids and splenectomy are less effective than in warm hemolysis. Splenectomy not useful b/c most hemolysis is occurring in the liver.
- Rituximab is useful
- Avoid cold exposure
- Transfusion, but warm up blood to above 30 deg frist.
4 causes of hemolytic disease of the newborn
Hereditary spherocytosis, low G6PD, alpha thal, maternal Ab incompatibility (by far the most common)
Erythroblastosis fetalis
Occurs in severe hemolysis. RBC precursors proliferate in liver / spleen and appear in the blood. Possibly leading to hydrops fetalis.
What causes physiologic jaundice of the newborn?
Complication
Low glucuronyl transferase.
May lead to kernicterus
Who should get RhoGam (Rh Ig)?
Unsensitized Rh- women after delivery, abortion, miscarriage, amniocentesis, or anything that might introduce fetal blood to maternal circulation.
3 mechanisms of drug-induced hemolysis
1) Drug binds RBC membrane, Ab binds to drug/membrane complex.
2) Drugs binds Ab in plasma, immune complex deposits on RBC membrane
3) Drug stimulates immune system to make autoAbs to RBC (true autoimmunity)
1) Drug binds RBC membrane, Ab binds to drug/membrane complex.
Drugs
Ig
Site of hemolysis
Beta-lactam AB’s
IgG
Extravascular
2) Drugs binds Ab in plasma, immune complex deposits on RBC membrane Drugs Ig Site of hemolysis What does DAT show?
Quinidine
IgM
Intravascular due to IgM fixing complement
DAT is positive for C3
3) Drug stimulates immune system to make autoAbs to RBC (true autoimmunity)
Drugs
Ig
Site of hemolysis
Alpha methyldopa
IgG (most often to Rh Ag)
Extravascular
