What is the mechanism of cross matching to prevent transfusion reaction?
I was doing this work in the mid ’70s so there may be some detail changes since. That being said: When a unit of blood was ordered for a patient I would take two samples, one from the patient and one from the donor unit. For each sample I would determine the blood type in a much more detailed way than we usually think of: I’d look for A/B/AB/O (O is really not A and not B), Rh positive or negative, then a dozen or so much rarer types; the ones I remember are Kell, Lutheran, Lewis and Duffy. If all of these were compatible, I would then perform a “direct agglutination” test which is the cross matching part of “T&C” or type and cross-match. I would put a little serum from the patient in a tube with a small amount of red cells diluted in normal saline from the donor unit. I’d mix these and then spin them gently in a centrifuge. When they came out of the centrifuge there would normally be a “button” of red cells at the bottom of the tube. If instead the cells had hemolyzed (burst) then the
