Are antibodies bad?
September 12, 2007 6:53 AM   Subscribe

What causes someone to develop antibodies in their system, and how important is it that their physician know about this?

Last Sunday a good friend of my parents was admitted to the hospital for many ailments. She also suffered a minor stroke within the last few weeks. She was also in the hospital for a week last month and prior to that hadn't seen a doctor in many years. My parents have been going to her house every day to feed the cat and look after her garden, as well as do some cleaning. My mother came across a letter, that was on the floor, from the Canadian Blood Services. My mother brought it home to see if I could understand what it meant. I tried googling, and couldn't come up with anything that made sense to me. It's been many years since I took Biology. I'm hoping that someone could shed some light as to what this means.

The letter states:

Your physician requested that a sample of your blood to be sent to Canadian Blood Services in CITY for routing testing. At that time an antibody was identified in your blood sample. This letter will provide you with some information about antibodies and contains an antibody card for you to carry.

You may have already some knowledge about blood groups such as A, B, O and Rd D positive or negative groups. In addition to these there are many other blood groups on human red blood cells. During pregnancy or following a blood transfusion a person may encounter red cells of a different blood group than their own and this sometime results in the formation of blood group antibodies. Seven percent of the population may develop antibodies in this manner. Antibodies are proteins in blood which don't normally cause any harm to the individuals who posses them. If blood, which is not matched for these blood groups, is transfused to a person with antibodies, it may cause a problem.

Attached is an antibody card which states your blood group and antibody you have formed. Please remove the card and keep it with you. Show it to the admitting department at the hospital and your doctor or nurse whenever you need medical attention that may require a transfusion.

Can someone explain this to me so that I can relate it to my parents? My initial reaction to this was that in the past she had a blood transfusion and was given the wrong blood type and she developed antibodies.

Should they advise her attending physician of this?
posted by cleo to Health & Fitness (13 answers total) 1 user marked this as a favorite
I would say that this part: Show it to the admitting department at the hospital and your doctor or nurse whenever you need medical attention that may require a transfusion. makes it pretty clear that her doctor should know about it.

I can't explain it but I think someone ought to give the letter and the antibody card to her physician.
posted by cooker girl at 7:05 AM on September 12, 2007

I strongly suspect you are referring to the Rh factor (also known as the Rhesus factor which is a blood grouping system that determines whether your blood is typed 'negative', 'positive' or 'neutral'.

It does sound like your family friend probably did receive some sort of blood product that wasn't typed and crossed, and/or she had a child that had a different Rh factor than hers and didn't receive medication to counteract the possibility of cross contamination.

This would probably help explain it better to your parents - it has lots of little charts with pictures to show how different blood types aren't always compatible.

The good news is that they've caught it and they can treat it appropriately. Make sure she has a good hematologist on board.
posted by dancinglamb at 7:06 AM on September 12, 2007

Oh, and most definitely, they should show that letter to their doctor. Any hospital worth their salt should have already figured this out, but better safe than sorry.
posted by dancinglamb at 7:07 AM on September 12, 2007

Blood groups are for many practical purposes largely a historical artefact. Whenever you receive a transfusion, except perhaps in extreme circumstances, the transfused blood is cross matched against your own blood, meaning that it is tested for a variety of antibody reactions. This testing includes for ABO system incompatibility and Rhesus, and some rarer antibodies. You never receive un-crossmatched blood, just on the basis of an old blood group result, and so knowing your actual blood group is quite unimportant. Having said that, if you have a very rare blood type, you might be in demand at the blood transfusion service, and if you have a "difficult" set of antibodies it might be hard to find blood for you in a hurry. Your mother's friend's doctors will want to note the results from the card in her hospital records, but they are unlikely to have any bearing on her treatment.

Disclaimer: I am not a haematologist, and there is at least one mefi immunologist who can probably explain this better.
posted by roofus at 7:32 AM on September 12, 2007

Uh, what cooker girl said.
Attached is an antibody card which states your blood group and antibody you have formed. Please remove the card and keep it with you. Show it to the admitting department at the hospital and your doctor or nurse whenever you need medical attention that may require a transfusion.
I'm really not understanding at all why this is a question. The answer to the question is printed on the card.
posted by dirtynumbangelboy at 7:57 AM on September 12, 2007

As an erstwhile immunologist, here's my 0.02usd.

Basically, any time your body has something foreign introduced into it your immune system labors to identify it and get rid of it. Antibodies are little Y-shaped proteins that stick to foreign things (think bacteria, and in this case foreign red blood cells) that trigger a response in the immune system so that it knows to purge the bit it's stuck to.

What it sounds like is that friend of yours did not have a bad reaction to whatever blood induced these antibodies (be it from a transfusion or from a past pregnancy) but her body wasn't entirely convinced that everything was okay. The problem occurs if she ever needs another transfusion - if she happens to be a blood type that is receptive to multiple blood types and she gets a transfusion of a blood type she has developed these new antibodies against, there could be a very bad immune reaction. These are important things to know, but in the meantime there's no real danger or anything to be concerned with (as far as I know, as a research immunologist.)
posted by oreonax at 7:57 AM on September 12, 2007

There are actually 29 recognized blood type systems in addition to the ABO and Rh systems mentioned above; they are listed here. Your friend could have been exposed to the antigens from one of those groups in a number of ways including prior transfusion and pregnancy. It is not a big deal to have these antibodies in day to day life, but if your friend ever needs a transfusion it is important. Sometimes it is only a minor hassle to find compatible blood, but sometimes it can take hours. In some cases people with difficult to match blood have their own blood frozen for future use. So definitely share the info, but it is something that the medical team will know how to handle with relatively little fuss.
posted by TedW at 8:02 AM on September 12, 2007 [1 favorite]

I'm with dirtynumbangelboy - I read this letter as a really verbose way of saying "below, find your blood type; show this to doctors to ensure you get the appropriate transfusion should it become necessary."
posted by rkent at 9:24 AM on September 12, 2007

Ted is correct. (I do this for a living.)

The most important thing for her to know is that she has an antibody. We will take care of the rest. The only time this could cause problems for her is when she needs to be transfused blood products. She already has a leg up on most patients because she knows that she has an antibody. There are a ton of folks running around who have antibodies and have no clue (usually multiparous women or folks who have received massive transfusions).

The reason that it is important is that if you are transfused blood and you possess an antibody to an antigen that is on those red cells, bad things can happen. If the antibody is IgM then it binds to the red cells and fixes complement and destroys the red cells. This is called acute hemolysis and is extremely dangerous. It can and will kill you or make you very ill. This is why you have to receive ABO compatible red cells, because everybody has naturally-occurring ABO antibodies (unless you are AB) and these are IgM (in most cases). Fortunately most other antibodies that are clinically important (for transfusion medicine) are IgG. These don't fix complement intravascularly, but they do cause you to clear the red cells from your system faster than you would otherwise (decreased survival in your system). While this is undesirable, it rarely causes any long-term damage.

The most important thing for your friend is that, prior to any surgery when she may need blood, she gives a blood sample to the blood bank at that hospital in advance (3 days). And that she makes sure they take enough blood from her (ie. 2 tubes) in order to do all of the necessary testing (we often have to request additional sample from a patient). That way they can re-identify that antibody, see if there are any new antibodies, and most importantly, locate blood that is antigen-negative for whatever antibody she possesses (eg. if she has an anti-Duffy a, they would crossmatch Duffy b + blood).
posted by i_am_a_Jedi at 9:31 AM on September 12, 2007

Also, she was probably never given the wrong blood in a transfusion before. Most likely, if she has had children, she was exposed to her partners antigens through the fetus. Or she received a transfusion of (ABO) compatible blood, that was positive for an antigen that she is negative for. When you receive a transfusion, you generally aren't matched for each antigen (or any antigens) other than your blood type, except in specific instances (like this one) or when the person is receiving chronic transfusions (eg. sickle cell patients).
posted by i_am_a_Jedi at 9:37 AM on September 12, 2007

What everyone else said, with the additional observation that while I understand that that letter is geared towards the layman, it's remarkably general to me -- it actually implies that your friend might have developed antibodies to the ABO blood group antigens. As the good Jedi mentioned above, pretty much everyone has antibodies to the ABO blood group (well, everyone who's A has antibodies to B, everyone who's B has antibodies to A, if you're O you have antibodies to both, and AB people have antibodies to neither), which is why we know about ABO in the first place... those omnipresent antibodies mean that transfusing blood mismatched for ABO is a fatal or near-fatal occurrence, and ABO discovery is what made blood transfusion possible in the first place.

Were I the Canadian health service official penning the boilerplate text for that letter, I'd probably word things differently to make that a little more clear...
posted by delfuego at 9:58 AM on September 12, 2007

i_am_a_Jedi has totally got it as far as what your friend needs to know and do. In case your friend (or you, or anyone) wants to understand more, I've written up a little explanation you can use. I have tried to make it readable and easy, and I've avoided jargon that any medical person would use, but I have not sacrificed any accuracy. So here's the story on blood types and antibodies.

First of all, do you know your own blood type? Your ABO blood type tells about some little markers that your cells display to identify themselves. If you have A blood, they display the A marker. If you have B blood, the B marker. AB blood means they display both and O blood means neither.

Antibodies are little Y-shaped particles that recognize some kind of marker and stick to it. Each arm of the Y is sticky, so each antibody can glue two things together. The idea is to stick germs together into great big tangles so your body can destroy them efficiently.

Well, what works on germs will work on blood cells, too. If you have the A or the B marker, you don't make antibodies against it, because they would clump all your blood up. But you do already make antibodies against the ones you don't have, because if that marker shows up, it obviously didn't come from you.

That's why they can't just give any person's blood to anyone else. If the blood has one of those markers and you put it in someone who has antibodies against it, the antibodies will glue all the cells up into clumps, and the body will destroy them, and then they're not doing any good. So they test blood for the A and B markers, and they test patients for the antibodies, so they know who they can give it to.

Now, how about the plus or minus after the A/B type? B+, O-, and all the rest of them. Know what it is? It's just another marker. It's called Rh. If you have it (you're Rh-positive), you'll never make antibodies against it. If you don't have it (you're Rh-negative), you can make antibodies against it—but not until your body has seen it once. Then if you're given Rh-positive blood again, your antibodies will kick in, just like they did with the A or B: clump and destroy. Doctors and nurses know all about the 'Rh factor', and they routinely test blood for it, too.

And now we've gotten around to this letter of yours. It turns out that A, B, and Rh are not the only markers that ever show up on blood cells. There are a couple dozen other ones. But they don't get as much attention, because they're rare or they don't cause as much trouble. The letter just says that you somehow started making antibodies against one of them. Probably you came into contact with some blood that had it sometime.

Now, that's not a problem, by itself. But if they ever happen to give you more blood that has that marker, your antibodies will glue it into clumps and it'll be no good. So you need to show this card to your doctor, and to anyone else who might give you blood. If you can do it ahead of time, give them a couple days. That way they know that there's one more test they need to do, at the same time that they're testing for A and B and Rh, and they can make sure that the blood they give is going to work for you. That's all.
posted by eritain at 2:46 PM on September 12, 2007

OK, actually, I did leave one thing out: Acute hemolysis. In the above, wherever it mentions that the blood cells clump up—it's not just that they aren't doing any good and that's a waste of time and expensive blood, it's also that breaking all those blood cells open is really really bad for you, and needs to be prevented.
posted by eritain at 2:54 PM on September 12, 2007

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