The Student Room Group

ABO blood

A bit confused.

Blood type O can be received by anyone, and blood type O creates anti-A,B antibodies. So how can it be taken in by those with blood type AB, as blood type AB reacts with anti-A,B antibodies?
Reply 1
booooost
Because it's not the red blood cells that create the antibodies, it's your body / white blood cells that do. A and B are two different types of proteins on the surface of blood cells, and your body will generate antibodies if it detects any of these proteins that you don't have. O blood means that the red blood cells lack these proteins alltogether so they don't trigger your body's immune system so it's fine.
Reply 3
Red blood cells have antigens (markers) on the surface, cells in groups A/B/AB all have different shaped antigens, type O red cells have no antigens at all. Antibodies are in the blood plasma (not on the red cells) and everyone has antibodies to whatever antigens their red cells don't have (so type O people have all the antibodies, types A and B have one type but not the other, ABs have none). Transfused blood contains red cells so you're putting the antigens on those cells into the recipient's plasma (therefore exposing them to their body's antibodies) - type O is the universal donor because there are no antigens on the red cells at all so whatever antibodies the recipient has won't have anything to react to. The antibodies are in the plasma not on the red cells so they don't travel with the donated red cells
Reply 4
Original post by Scotland Yard
Because it's not the red blood cells that create the antibodies, it's your body / white blood cells that do. A and B are two different types of proteins on the surface of blood cells, and your body will generate antibodies if it detects any of these proteins that you don't have. O blood means that the red blood cells lack these proteins alltogether so they don't trigger your body's immune system so it's fine.

but if you're donating your blood, which includes the plasma and all the antibodies inside it, wouldn't O blood have antibodies when someone being exposed to A and B since they're both antigens it doesn't have?

I think I've figured it out though, correct me if im wrong. I realised blood type O has ANTI-A,B antibodies. Meaning its not A,B antibodies that binds to A or B antigens, but its antibodies that bind to antibodies that are against A,B, so basically it stops there being a reaction whenever A or B antigens are exposed to the body. I mean it makes sense bc if our body is exposed to new antigens that are harmless, it doesn't make sense for it to be attacking it constantly surely?
Reply 5
Original post by JaceW98
Red blood cells have antigens (markers) on the surface, cells in groups A/B/AB all have different shaped antigens, type O red cells have no antigens at all. Antibodies are in the blood plasma (not on the red cells) and everyone has antibodies to whatever antigens their red cells don't have (so type O people have all the antibodies, types A and B have one type but not the other, ABs have none). Transfused blood contains red cells so you're putting the antigens on those cells into the recipient's plasma (therefore exposing them to their body's antibodies) - type O is the universal donor because there are no antigens on the red cells at all so whatever antibodies the recipient has won't have anything to react to. The antibodies are in the plasma not on the red cells so they don't travel with the donated red cells


ohhhhhh this makes sense. Wait so donated blood is JUST red blood cells then? All this time I thought it was the plasma too with antibodies and what not, because I just assumed it would take long to separate them out, my bad

thank you
As @JaceW98 explains in some detail above, the point to remember is that the blood seen as "foreign" is the transfused blood i.e. the donor blood NOT the recipient blood. Therefore, any transfusion reaction that might occur is an immune reaction of the recipient against the donor, NOT THE OTHER WAY ROUND, yeah? Therefore, since O blood cells have NO antigens, if O blood is transfused into the bloodstream of a patient with ANY ABO blood group, there are no antigens on this O blood's cells to provoke an immune response from the body of the recipient.

REMEMBER, OC THAT THE ABO BLOOD GROUP SYSTEM IS NOT THE ONLY ONE AND A TRANSFUSION REACTION CAN OCCUR DUE TO E.G. RHESUS INCOMPATIBILITY EVEN IF THE ABO GROUPS ARE COMPATIBLE E.G. IN HAEMOLYTIC DISEASE OF THE NEWBORN, which can occur in a Rhesus negative mother carrying a Rhesus positive baby. Here the mother's own antibodies attack her baby's cells.

M
Reply 7
Original post by Anonymous
ohhhhhh this makes sense. Wait so donated blood is JUST red blood cells then? All this time I thought it was the plasma too with antibodies and what not, because I just assumed it would take long to separate them out, my bad

thank you


Donated blood has a little bit of the donor's plasma in too, but it's so little when combined with the recipient's plasma the effects are negligible (although they do technically still happen on a very minor level, which is why it's slightly preferable to receive a donation from your own blood group and why they bother typing patients at all rather than just pumping everyone with O-), and antibodies are flushed out of the body pretty quickly anyway so any that came along with the donor red cells wouldn't stick around that long.

Donor plasma also exists (mostly used for burn victims and various blood clotting disorders) and is typed the other way round from blood - they get that from regular blood donations by filtering out the red cells.

While we're on the topic please donate blood if you're able, it's very important!
(edited 11 months ago)
Original post by Anonymous
ohhhhhh this makes sense. Wait so donated blood is JUST red blood cells then? All this time I thought it was the plasma too with antibodies and what not, because I just assumed it would take long to separate them out, my bad

thank you



Hang on a sec young man/lady don't get confused!

Tho the answer by @JaceW98 is correct in principle, you must remember that a blood transfusion usually involves the "infusion" [almost like injection into a vein kinda] OF WHOLE BLOOD [transfusion with red cells alone is used much less commonly under specific situations], so donor plasma DOES GO INTO THE RECIPIENTS BLOODSTREAM, TOO - however, the reason there is no transfusion reaction when O blood is donated is explained more precisely in my first post above. Check it out!
Reply 9
Original post by macpatgh-Sheldon
As @JaceW98 explains in some detail above, the point to remember is that the blood seen as "foreign" is the transfused blood i.e. the donor blood NOT the recipient blood. Therefore, any transfusion reaction that might occur is an immune reaction of the recipient against the donor, NOT THE OTHER WAY ROUND, yeah? Therefore, since O blood cells have NO antigens, if O blood is transfused into the bloodstream of a patient with ANY ABO blood group, there are no antigens on this O blood's cells to provoke an immune response from the body of the recipient.

REMEMBER, OC THAT THE ABO BLOOD GROUP SYSTEM IS NOT THE ONLY ONE AND A TRANSFUSION REACTION CAN OCCUR DUE TO E.G. RHESUS INCOMPATIBILITY EVEN IF THE ABO GROUPS ARE COMPATIBLE E.G. IN HAEMOLYTIC DISEASE OF THE NEWBORN, which can occur in a Rhesus negative mother carrying a Rhesus positive baby. Here the mother's own antibodies attack her baby's cells.

M


Original post by JaceW98
Donated blood has a little bit of the donor's plasma in too, but it's so little when combined with the recipient's plasma the effects are negligible (although they do technically still happen on a very minor level, which is why it's slightly preferable to receive a donation from your own blood group and why they bother typing patients at all rather than just pumping everyone with O-), and antibodies are flushed out of the body pretty quickly anyway so any that came along with the donor red cells wouldn't stick around that long.

Donor plasma also exists (mostly used for burn victims and various blood clotting disorders) and is typed the other way round from blood - they get that from regular blood donations by filtering out the red cells.

While we're on the topic please donate blood if you're able, it's very important!

ahhh thank you both!!! I think its bc I just thought that donating blood was only donating the RBC in the plasma with everything else, everything else you guys said makes sense now

and yess I need to do that, im not sure if I'll be eligible as I was anemic last time I checked but I think my iron levels are fine now

again, thanks to everyone on this thread!!
Reply 10
Im not gonna lie I think I finally understood using this table (if anyone is in the same situation as me, hear me out)

basically in the antibodies column, notice how all the rows say 'anti - ___', meaning it is an ANTI- xyz ANTIBODY. O has anti- A,B antibodies, meaning that it targets antibodies that target A and B, stopping those antibodies that bind to A or B from actually binding to it.

To me that makes sense, as if I had blood type O that was exposed to A and B antigens that are harmless, it wouldn't make sense for my body constantly fighting them off. So to prevent my body having a reaction to A or B antigens, I would have ANTI-AB antibodies

the only time when the antigens on the RBC react, is when it is an _-antibody (for example antibody A would react with blood type A). This would try and get rid of whatever it is targeting.

So a person with blood type AB, receiving blood type O, is fine as blood type O does not have A or B antibodies, but in fact ANTI-A/B antibodies

if this is not correct then I give up because this is the only way it made sense to me lol
Reply 11
the table didn't even attach, so I've tried uploading it as a link

https://ibb.co/ZmZqKBp
Reply 12
Original post by Anonymous
ahhh thank you both!!! I think its bc I just thought that donating blood was only donating the RBC in the plasma with everything else, everything else you guys said makes sense now

and yess I need to do that, im not sure if I'll be eligible as I was anemic last time I checked but I think my iron levels are fine now

again, thanks to everyone on this thread!!

You should be eligible if your iron levels are ok (barring other things that would exclude you obviously), maintaining a good diet coming up to your donation will help with the iron levels - bear in mind though that 3 instances of anemia when trying to donate in a row will get you a long-term ban from the donor register, so it's always good to check your levels are ok before booking a donation (and to avoid wasting the appointment).

If you're type AB look into donating plasma or platelets instead of whole blood - as we've established these are typed the other way round so AB people are the universal donors, and there's a real shortage of both, especially platelets
Reply 13
im so dumb sorry, watched my lecture back and turns out she was speaking about red blood cell transfusions this whole time :smile:

so I was literally on the edge for a good 2 hours over this:smile::smile::smile::smile::smile::smile::smile::smile::smile::smile::smile:

thanks all ignore everything

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