Blood antibodies, immunohematology

One of the parents of a friend of Zyle's in his class at school works for a company involved in blood testing. She offered some *informal* education. I recognize that the parts that offer possibilities for what's going on with Zyle shouldn't be taken as diagnosis and is based on some assumptions, including my own assumptions in my previous post about the inheritance of factors. We don't know for sure this is what's going on; we weren't even talking directly to the people doing the lab work. However, it helped me understand a lot better:


Christie said:

"Here's a quick run-down in immunohematology....hopefully this will help you guys with a baseline in case you face more issues with getting compatible units for Zyle and need a translation for blood bank talk:

"Typically, when you test a patient's blood before a transfusion, you perform what's called a "type and screen". A type and screen is 2 essential tests - the blood type and the antibody screen: Details on the type: As you know, everyone has a blood type such as A Positive, B Negative, etc. The letter (A, B, or O) designates your blood group, and the Positive or Negative designates your Rh type, which is the presence or absence of the D antigen on your red blood cells. Essentially, A, B, and D are all antigens that commonly exist on our red blood cells through genetics, if you don't have the antigen on your red cells, then you have that antibody in your plasma or serum. For example, an AB Positive person has the A antigen, B antigen and D antigen on their red blood cells, and they don't have any of those antibodies in their plasma. An A Positive person has the A and D antigen on their red cells, and the B antibody in their plasma. An O Negative person has none of these antigens on their red cells, and the A, B and D antibodies in the plasma. It's important that we get the blood type right in a transfusion, because if you transfuse a unit of blood into a person that doesn't have the matching antigens, then they have antibodies against those antigens in their plasma which will attack the transfused red blood cells and cause hemolysis, or destruction of those cells upon transfusion. So in the example of an A Positive person above, if we transfused that patient with B Positive blood, the naturally occurring B antibody in the patient's plasma attacks the B antigen on the red cells in the donated unit and destroys all of the red cells in the transfused unit. Based on what you posted on your blog, it sounds like Zyle is Rh negative and both you & Seth are Rh positive, which means that you don't have a compatible blood type and can't donate units for Zyle.

"Details on the antibody screen: In addition to the blood type, we also screen all patients and blood donors for the presence of unexpected antibodies. We expect all patients to have a blood type with one of the A or B antigens (or lack of both which is blood group O) and the Rh antigen (D), but there are also many unexpected antibodies that some people have - typically these are obtained through being previously transfused (which is why they kept asking you if Zyle had a blood transfusion before) or sometimes they occur for other reasons. There are over 30 of these unexpected antibodies - they have names like Anti-K, Anti-C, Anti-E, Anti-c, Anti-e, Anti-Fya, Anti-Fyb, Anti-Lea, Anti-Leb, Anti-K, Anti-k, etc. About 95% of patients have a negative antibody screen, and you move on and just give the patient type-specific blood that matches their blood group and type. But if an antibody screen comes back positive, then they have to do a second test to identify the antibody called an antibody identification, and then you have to find a unit of blood that is antigen-typed to be negative for the antibody that the patient has. Based on the fact that they are having a hard time finding compatible units for Zyle, it sounds to me like he may possibly have an antibody and they are having to bring in antigen typed blood that specifically matches for the rare antibody that he has. I would ask for more details on this...."