Immune Hemolysis Flashcards
What types of antibodies does the DAT (Coombs) Test detect? Where is the antibody?
IgG antibodies or complement C3 on patients red cells
What types of antibodies does IAT (Coombs) Test detect? Where is the antibody?
detects IgG antibodies against RBC, its found in the patient serum
Where does the majority of immune hemolytic anemia occur- extravascular or intravascular?
mostly in extravascular (Ab-coated RBC ingested by macrophages) with the exception of ABO transfusion rxn
Which antibody are the spleen and liver best at removing from the blood?
spleen is most efficient clearing RBC coated with IgG and liver is more efficient in clearing sensitized by IgM (and complement over C3)
Name some common causes of autoimmune hemolytic anemia.
many are idiopathic, other are associated with autoimmune disease, lymphoproliferative disorder (esp CLL) infection, etc.
What smear/lab results would be suggestive of hemolysis due to warm autoantibodies?
DAT will be positive for IgG +/- C3 peripheral blood shows spherocytes, not bite cells, young shift cells may be present
How might you treat someone with hemolysis duet o warm autoantibodies?
corticosteroids splenectomy (relapse) rituximab transfusion (although crossmatch may be difficult)
Cold agglutinin syndrome is _____ antibody-mediated.
IgM, and most commonly target I or i antigens Note: hemolysis is more likely if antibody binds RBC at or near body temperature (measured by thermal amplitude), most are clinically benign
Cold agglutinin syndrome can be a complication of the which infections?
mycoplasma, EB virus or lymphoproliferative disorders
What is the smear/lab result indicating cold agglutinin (think antibodies).
DAT positive for C3 and negative for IgG smear shows groups of RBC that appear to be clumping together, clumping can be seen macroscopically
What is acrocyanosis?
slugging of blood that may occur with cold agglutinin syndrome can be clinically apparent with livedo reticular or associated with Raynaud’s syndrome
What can we do to treat cold agglutinin disease?
alternative immunosuppression and avoid cold exposure (corticosteroids or splenectomy are often ineffective)
Given the mechanism of drug-induced hemolysis, name the likely antibody and location of hemolysis: drug binds RBC membrane, antibody binds to drug-membrane complex. (haptenic)
IgG antibody, extravascular hemolysis (often Beta-lactam)
Given the mechanism of drug-induced hemolysis, name the likely antibody and location of hemolysis: drug binds antibody in plasma, immune complex deposits on RBC membrane. (immune complex)
IgM antibodies with complement fixation, intravascular hemolysis (often quinidine)
Given the mechanism of drug-induced hemolysis, name the likely antibody and location of hemolysis: drug stimulate immune system to make autoantibodies.
IgG antibodies, extravascular
