Q. I’m currently doing my rotations at Children’s Memorial Hospital’s blood bank and I was reading the standard operating procedure for washing red cells. One of the conditions in which they need to be washed is paroxysmal nocturnal hemoglobinuria. Do you know why this is?
A. The reason for washing red cells for people with PNH is to get rid of any ABO incompatible plasma.
In a person without PNH, ABO incompatible plasma doesn’t cause any perceptible hemolysis. The antibodies in the donor unit probably just get diluted out enough that they don’t have much of an effect. Or perhaps they get sopped up by other ABO antigens on other cells (did you know that you have A and B antigens on cells besides red cells?! Weird.).
But patients with PNH are super susceptible to complement-induced red cell destruction. They lack the ability to anchor certain proteins (including proteins that protect the red cell against complement) to the red cell membrane. Patients with PNH have a hard time down-regulating even a small amount of complement activation – so theoretically, a transfusion of even a small amount of non-ABO compatible plasma could lead to hemolysis. There have been a few cases of hemolytic transfusion reactions in patients with PNH that have been attributed to this phenomenon…so in 1948, blood banks began washing red cells before giving them to patients with PNH.
- Paulinus said Such an excellent CV. Thank you for all you are doing to make learning pathology so simple.
- Anna das said Thank you
- Brian E. Moore, MD said Brilliant explanation!
- Anon said Isn’t anti- A,B an expected antibody, just as anti-A and anti-B are, due to plant lectins (bas...
- rashid said Awesome
- Dr.Govind said excellent explanation thank you very much.
- Dr.Govind said nice
- nouf said 🙂
- Dr Govind said very simple explanation thank u very much..
- Dr Govind said nicely explained.
- Ana said Dope!! I love your summary….keep it up
- Kristine said Hi Michelle – thank you so much for your kind words! I’m SO glad you find useful stuff o...