Kidd blood antigens can cause trouble for transfusion patients

DEAR DR. ROACH

» I had two blood transfusions in 2012 during an almost yearlong bout with an out of control infection that ended up in a fused knee.

In a recent antibody screen, I was identified as having antijkb. The information on this that I was able to find on the internet was incomprehensible to me. In simple terms, what does this mean? Am I able to donate blood? Can I receive donated blood?

— S.L.

ANSWER » Most people know about the ABO blood types and the Rh factors that are the primary considerations that govern how we can transfuse blood, but there are many other blood antigens that can also cause transfusion reactions. “Antigen” is a general term for a substance than can provoke an immune response, usually a protein, sometimes connected with sugars. One of the families of antigens that may cause a transfusion reaction is called the Kidd blood group system. It’s named after the first patient in whom this was found.

Antibodies to these antigens can cause transfused blood to be destroyed. This is called a hemolytic — literally, “blood-breaking” — transfusion reaction. Worse, Kidd antibodies (anti-jka, anti-jkb and anti-jk3) can be difficult to find. The level in the blood goes down to very low, sometimes undetectable levels after transfusion, but the antibodies are still capable of causing a transfusion reaction. The transfusion reaction in this case is typically delayed, not immediate.

For this reason, it would be worthwhile for people with anti-Kidd antibodies to wear a medical alert bracelet in case of emergency transfusion need. People like you, with anti-jk antibodies, may still donate blood, but the blood bank must give this blood only to people who lack the antigen.

Contact Dr. Roach at ToYourGoodHealth@med. cornell.edu.