Immunohematology- ABO blood group systems Flashcards
(16 cards)
What is immunohematology?
It’s the study of antigen-antibody systems related to blood groups, involving antigens, antibodies, immunological reactions, blood group systems, serological techniques, and clinical implications.
What type of antibodies are commonly found in the ABO system?
Naturally acquired IgM antibodies that optimally agglutinate at 16–22°C.
What does Landsteiner’s law state?
If A and/or B antigens are absent from red blood cells, the corresponding antibodies will be found in the plasma.
What antigen and enzyme are found in Type A blood?
Type A has the H antigen and A transferase, which adds N-acetylgalactosamine (GalNAc) to form the A antigen.
What antigens are present on red cells of a person with Type AB blood?
Both A and B antigens, as both A and B transferases are inherited.
What antigen and enzyme are found in Type B blood?
Type B has the H antigen and B transferase, which adds galactose to form the B antigen.
What is the Bombay phenotype?
A rare condition where a mutation in the FUT1 gene prevents H antigen expression, so A and B antigens can’t form. These individuals appear as Type O but have anti-A, anti-B, and anti-H antibodies.
What gene encodes the H antigen and what enzyme does it produce?
The FUT1 gene on chromosome 19 encodes α1,2-fucosyltransferase, which adds fucose to the precursor chain to form the H antigen.
Why do Type O individuals lack A and B antigens?
They lack both A and B transferases, so only the unmodified H antigen is present.
Why is ABO compatibility critical in transfusion?
A mismatch can cause severe or fatal immune reactions, so matching blood group is essential.
What are the common reasons for red blood cell transfusion?
To correct anemia, during surgery, for bleeding episodes, or to maintain hemoglobin in cardiac patients.
What are the storage conditions for red blood cells?
Stored at 2–6°C with a shelf life of 35 days.
What are the main indications for fresh frozen plasma (FFP) transfusion?
To replace clotting factors in liver disease, DIC, or massive bleeding.
How is FFP stored and what is its shelf life?
Stored at -25°C with a shelf life of 36 months.
How are platelets stored and what is their shelf life?
Stored at 20–24°C with a shelf life of 5 days.
Why are platelet transfusions given?
For bleeding, clotting issues, chemotherapy, surgery, or DIC.
