Basically title! I was wondering about this. Thanks!
In: 144
Source: I work in a blood bank at a hospital!
Some patients do! However, the type of immune response you get with blood transfusions are different than the kind you see with solid tissue just due to the difference in time and length of exposure and how easy it is to remove the offender from the body.
A semi-common transfusion reaction is actually hives/allergic reaction and some patients need to be pretreated with benadryl or antihistamines before transfusions.
Your immune system, specifically the adaptive immune system that is the main culprit in organ rejections, works by exposure and response. The body is exposure to a foreign something (like tissue from another person), it realizes that it’s foreign, and it starts to build an attack to it. This process takes time, although in some cases it happened quickly if the body has been exposure to something similar enough in the past that it basically can take a shortcut.
Blood transfusions are a single exposure to foreign stuff that don’t last long in your body. In fact, something like platelets which have a max lifespan of 7 days, so it’s gone from your body before your immune system has even figured out something weird happened. These are human cells, so it takes time for the body to realize that these human cells aren’t it’s human cells and for the immune system to go into attack mode. So most people don’t mount an immune response to blood transfusions whether platelets or red blood cells.
However, the immune system can! And does! For platelets, this normally shows up by decreased response to transfusion (basically the patient’s platelet count didn’t increase as much as it should). The body destroys the transfused platelets and removes them from the blood. This doesn’t normally cause any other major issues.
Red blood cells however are quite different. In order to receive crossmatched red blood cells (basically the standard for red blood cell transfusion that are nonemergency), you have to have blood bank testing. This testing includes a blood type and an antibody screen.
There are naturally occurring red blood cell antibodies. These are actually antibodies against sugars on bacteria you’ve been exposed to BUT these sugars can be found on red blood cells (or are similar enough) so they attack red blood cells too. However, the presence and absence of these antibodies are predictable based on blood type and can be detected by doing blood type testing. Group A blood types have anti-group B antibodies and part of providing someone is Group A is showing they have anti-B. So we know not give Group B blood to a Group A (that would trigger an immune response and be Very Bad).
There are non-naturally occuring red blood cell antibodies too. These are detected by the antibody screen and then identified. These are formed after the immune system has been exposed to red blood cells that are foreign either through transfusion or pregnancy. Some can also be trigger by other stuff, like exposure to a weird drug or bacterial that forms antibodies that have cross reactivity with red blood cells.
Antibodies are (mostly) specific, so they attack a specific aspect of the red blood cells that triggered the response. Through research, these immune system triggering aspects (aka antigens!) have been classified into various blood group systems (there’s a lot more than just the ABO blood groups you’re probably familiar with!). When a patient is found to have antibody, they get blood that DOESN’T have that aspect that triggers the immune system. We make sure the blood doesn’t have it by testing it. We also test the red blood cells that are going to be transfused against the patient’s plasma that contains the patient’s antibodies. If there is a reaction, then that blood is NOT given to the patient. If there is no reaction then the blood is as safe as we can prove and it’s assigned to the patient.
In an emergency situation, there may not be time to do testing before the patient bleeds out. So they get O Neg (or in some cases O Pos) because that is the safest blood type when considering just ABO groups. Most people have not been previously transfusion and therefore do not have non-naturally occuring antibodies, so the risk is minimum. But not zero.
If that patient did have antibodies, and the blood they were given reacted with those antibodies, they have a transfusion reaction. This reaction is their immune system destroying the red blood cells which causes all kinds of symptoms. At that point, you just treat the transfusion reaction and it’s symptoms – you can’t really do anything to stop it. Unlike a solid organ that remains in place and can continue to trigger the reaction thus making it worse and worse, blood is filtered by the body all the time and old, dying, or antibody covered cells are removed from the blood stream. So the trigger is naturally removed and there isn’t any long lasting presence that requires immunosuppressants.
Can you tell I like blood banking? Because I do.
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