Thread: Blood Group

I was just thinking that on what base is the blood groups are differentiated as B+ve, B-ve, etc..

Thanks for any help.

Your blood is taken and mixed with a known source of the various blood antigen antibodies. It becones apparent which type of blood type you are by observing if agglutination occurs or not.

Im not 100% sure but I think that it has got something to do with the shape of the platelets. Of course....feel free to correct me if someone knows better than I.

I though it was the presence and absence of certain hormones

ok hold on. You're both wrong. Blood groups are based on the presence/absence of proteins on your blood cells (including red, white & platelets). If protein A is present, you are blood group A, the same idea for group B. AB for both, O for neither.
(Im not bothering to explain the rhesus fctor)

If you are missing a protein, eg no protein A, then the A antibody will be present in your blood. This will cause an agglutination (clumping of erythrocytes) if erythrocytes with this protin were introuced into the blood.

So, in the lab, they test for the presence of the protein/antibody by placing a blood sample into variou petri dishes containging the known appropriate antibody. If agglutination occurs, then the blood sample contains that protein an the person has that blood group.

eg, if a samle of A blood is placed into anitbody A and aggluination occurs, the the person is blood group A. Is this clear?

Yes it is, thanks

Originally Posted by Nevyn

I though it was the presence and absence of certain hormones

Yeah to certain extent well the details

revealed in the concept of science do

some times makes people go feel amazing...

So what difference would it make if you had protein A or protein B, would your blood function differently?

No, not at all, they're just different proteins found on your blood cells, they dont really do anything normally.

Hi, I'm new to this forum and I've browsed a bit, and I think i might elaborate a bit more on this subject, having seen this in school this week.

Basically, it's as Robbie said.
The erythrocytes (red blood cells) are made up of haemoglobine in the center and of course a lipid membrane, in which several proteins are embedded. Among these proteins, are the so-called antigenes. 2 kinds exist, antigen A and antigen B. They are both very similar. The only difference between the 2 is the terminal sugar of the six-unit carbohydrate portion of the molecules. Enzymes encoded by the ABO gene add these terminal sugars to a common precursor called the H-substance : a terminal galactose-unit for the B antigen and a terminal N-acetylgalactosamine-unit for the A-antigen.

If your erythrocytes have the A-antigen in their membranes, your bloodserum will have the B-antibodies, because A-antibodies and A-antigen will couse agglutination. If B-antigen is present on the erythrocyte, A-antibodies will be present in your bloodserum. People with both A and B -antigen will have bloodtype AB, and will have neither antibodies in their serum, to prevent agglutination of their own blood. People with bloodtype O, have A-antigen nor B-antigen on their erythrocytes, and thus will have both antibodies in their serum.

You can figure out the problems with bloodtransfusion:
Someone with bloodtype A (and B antibodies in their serum) can't get blood from someone with bloodtype B, because the antibodies present in his serum will agglutinate all of the 'new' blood. People with bloodtype AB have no antibodies, and thus are the perfect receptors, meaning they can get blood from anyone (Rhesus factor aside...). People with a bloodtype O have no antigens on their erythrocytes (at least not A or B) and thus are the perfect donors, because the erythrocytes from the donor can't be attacked by the antibodies of the receptor. The antibodies of the donor might interfere a bit with the antigens of the receptor, but i reckon this is negligable.

If I'm wrong, please correct me, because I have to learn this for my exams

Cheers

The antibodies of the donor might interfere a bit with the antigens of the receptor, but i reckon this is negligible

thatsthe interesting thing, yes here may be some antibody-antigen reaction due to the donor blood (which is why type secific is always preferable,) but the reactions can vary from mild jaundice to shock & death[/quote]

Sure, it is sugar who is responsible for blood groups, not proteins !

Where does the Rhesus factor come into play? (eg. + vs. -) In other words, why does it exist? What is its significance? how do they test for that exactly? And how does it affect blood transfusions?

(I also heard that if a mother is expecting and she and the child have incompatible rh factors her body will attempt to abort the baby -- assuming that it's foreign matter. Even if the mother's body doesn't do this, developmental problems can occur) why does this happen?

The Rhesus protein is just another protein, its very similar to the ABO groups. It was discovered on rhesus monkeys; hence the name. It is also reffered to as antigen-D or anti-D.
It's significance is pretty much the same as ABO, if it is present in donor blood, it can cause a reaction in the recipient (who has the antibody)

What you're referring to is haemolytic disease of newborn, if a mother is Rhesus negative (Rh-) and the baby is Rh+, the mother's blood will begin to produce a lot of the antibody against the antigen when the baby is in the womb, this is fine for the first, or even the second baby, but in subsequent pregnancies, there will be enough antibody in the mother's blood to attack the baby's blood. This can result in enlarged spleen, jaundice and death of the baby.

The cure is to give the mother antibody-D antibody, (an antibody against the rhesus antibody the mothr has been producing) so that for each pregnancy, her production of antibodies will restart preventing this reaction occuring against the baby.

Thank you Robbie, that explains a lot.

I have another question, too. I'm not sure how credible this is, but I was listening to a friend talk about the "blood type diet." Supposedly, type O's need a high protein diet, is this because they lack A or B proteins? Type A's need a more veggie-centric diet, and they have antigens. AB types are pretty versatile and they've a diverse collection of antigens.

Maybe this is off the wall. I'm quite new to the sciences (I've an arts degree) so please forgive me.

Yeah this is to do with the origin of the various blood proteins, I THINK, blood protein A comes from Asia where their diet consisted mostly of grains and blood protein B is European who eat dairy; now some people think this has some sort of relevance to personalised diets. personnally I think its rubbish but it sounds good to people trying to create a fad diet. Im not actually sure on the details of it, but I'll read up and get back to you.