Use of Type O is limited by its Rh factors


October 16, 1990|By Dr. Simeon Margolis

Q**You recently said people with Type O blood are universal donors. Isn't it true that the use of O, Rh positive blood in an Rh negative recipient, can create problems?

A**That's correct.

Type O individuals are universal donors only with respect to the AB blood group antigens. Recipients of a blood transfusion, especially those who have had prior transfusions, may have produced antibodies against one or more of the many other antigens that can be present on the red cells of the transfused blood and lead to serious reactions.

The most potent of the other antigens on red cells is the Rh antigen D. Individuals are termed Rh positive when their red cells contain this antigen.

Those lacking antigen D develop antigens against it only when exposed to Rh positive blood during a transfusion or when pregnant with an Rh positive fetus. Transfusion of O, Rh positive blood into an Rh negative donor, may cause a reaction or the new production of antibodies against antigen D.

Donors and recipients are always tested for Rh type as well as ABO type. Only blood compatible with both these blood type systems is used for transfusion.

*Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine and associate dean for academic affairs at the school.

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