Kell blood group and rare blood groups

Kell blood group

Of Finnish blood donors, 96% are Kell negative and 4% are Kell positive (i.e. positive for the K-antigen in the Kell blood group system).
K positive red blood cells can be given to anyone who needs blood, but a small percentage of K negative individuals will subsequently develop antibodies to the K antigen. Patients who have been diagnosed with anti-K antibodies should always be given K negative red blood cells.

The anti-K antibodies that have formed do not cause any problems in blood transfusions, since most (96%) donated blood is K negative. It is therefore not difficult to find K negative blood.

Antibodies, on the other hand, are significant during pregnancy. If a K negative mother has formed antibodies to the K factor and the foetus is K positive, the mother’s antibodies can cause the foetus’ blood cells to break down. For this reason, all girls and women of childbearing age are always given K negative red blood cells. The use of K negative blood products may also be considered for patients who receive repeated blood transfusions.

Donated K positive blood is given to patients just like K negative blood. 4% of Finns who need blood products are also K positive.

Rare blood groups

In addition to basic blood groups, people also have other blood group factors. Some of them are rare. Rarity can also manifest itself in such a way that a person does not have a blood group factor, which is very common in humans. Examples of rare blood groups are Jk-3, k neg, Vel neg and U neg.

Blood group factors other than ABO and Rh D may be important if, for example, a patient has developed antibodies against a particular blood group, or has to undergo repeated transfusions involving large amounts of blood.

Sometimes, international cooperation between the world’s blood services is a prerequisite for being able to help a patient.