Ann needs a blood transfusion. Ann has blood type A-. Three of Ann\'s friends ha

Question

Ann needs a blood transfusion. Ann has blood type A-. Three of Ann's friends have offered to donate blood for her transfusion. Marie has B and Rh antigens on her RBCs, Katie has A and Rh antigens on her RBCs and Mark has A antigens on his RBCs. Based on this information answer the following (number your answers).

1. List the blood type of each friend

2. List the type of antibody of each person including Ann (assume everyone has been exposed to Rh factor)

3. Explain who would be the best donor and why (be specific)

Explanation / Answer

1. & 2. There are mainly 4 types of human blood. A, B , AB and O. Now, these could be Rh positive/ negative.

Rh factor is inherited from parents. It is a protein present of the surface of RBCs. If this is present on the RBC surface, the blood type is called Rh positive and if that protein is not present, then it will be called Rh negative.

Now how are these blood type A, B, AB, O determined? They are differentiated based on other type of RBC cell surface antigens. For blood group A, there is specific A antigen present on the cell membrane & antibody B present in the serum. For group B, antigen B is present on cell surface and antibody A is present in serum. For AB, both antigen A& B present but no antibody is present in serum. For, O group, no surface antigen present but both antibodies A and B are present in serum.

Marie has B and Rh antigen. It means that B antigen is present on cell surface and antibody A is present in serum & Rh factor present. So, her blood group is B positive.

Katie has A antigen in cell surface and Rh factor. That means that she has B antibody in serum. So she has A positive blood.

Mark has only A antigen (and he also has antibody B) that means he has no Rh factor. So, he will have A negative blood.

Ann has a blood type A negative. Blood type A means, it has cell surface antigen A and serum antibody B and also Rh factor absent because it is denoted as negative.

3. Think of a situation. A critically injured person had blood group A and he was given group B blood. So, we know that antibody works against antigen. Now, antibody B of serum of that injured person will work against antigen B of blood group B. That will lead to coagulation and ultimately he'll die.

Same situation applies with Rh factor. If a person who has no Rh factor/ Rh negative and he is given Rh positive blood, that will lead to death similarly due to coagulation.

Exact match for Ann is Mark. Because both of them have A negative blood. Rh is present in neither of them. So, it is safe. And again, antibody B present in Ann's body which will react against Antigen B but Mark's blood has no antigen B( as he has blood group A with surface antigen A). So no reaction would occur and this would be the best choice of donor.

However, Marie will not be a choice because she has antigen B. Ann's antibody B will work against Marie's blood.

And in case of katie, although she has A group, her blood has Rh factor. But Ann has no Rh factor. So, katie is not a safe choice as donor.

Mark would be the best choice.

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