Autoantibodies Flashcards
What are the scenarios when you should suspect an Autoantibody? (3)
- Positive DAT
- Anemia w/ reticulocytosis or microspherocytosis (DAT will confirm/exclude autoimmune hemolysis)
- Positive autocontrol in Antibody Panel (DAT will ensure that reaction is immune mediated)
A DAT reactive with anti-IgG only or with both anti-IgG and anti-C3, what is the most likely cause?
*What should be performed next?
Warm autoantibody (IgG)
*Elution should be performed on all positive IgG DAT results
A DAT reactive with anti-C3 only, what is the most likely cause?
Cold autoantibody (IgM)
A Positive DAT on cord blood is likely the result of what?
Maternal alloantibody or RhIg
A positive DAT with both clumped and unclumped cells is called what?
-What is the likely cause?
“Mixed Field” pattern
-Recently transfused blood
Warm reacting Autoantibodies:
- Optimal Temp
- Type of Ab
- React with? (2)
- 37C
- IgG
- React with patients own RBCs (positive autocontrol/DAT)
- Panreactive with all cells tested in screen, panel and crossmatch
What correlates with the likelihood of hemolysis in warm reacting autoantibodies?
Presence and strength of anti-C3
What are the most commonly encountered autoantibodies?
Benign Cold Agglutinins
Cold Reacting Autoantibodies:
- Optimal Temp
- Titer of Benign
- Type of Ab
- 4C (have wide thermal amplitude, up to 22C)
- <64 at 4C
- IgM (can activate complement in vitro)
Cold Reacting Autoantibodies reactions are seen at the ___ phase using ________ antisera.
AHG phase using polyspecific antisera
What are the findings in Cold Reacting Autoantibodies reactions using Monospecific reagents?
Cells agglutinated by anti-C3d
-NOT anti-IgG
Antibody specificity of benign cold agglutinins is most commonly what?
Anti-I
The I antigen is strongly expressed on what?
-Weakly on?
Adult Red Cells
-Weak on Cord Red Cells
What Ab reacts with cord blood, but not with adult blood?
Anti-i
Anti-H reacts best with what blood groups?
O and A2 red cells
