Rh Factor: Origin and Significance of the Rhesus Antigen

The term Rh is used because the antigen was first discovered in blood of a rhesus monkey.

The Rh factor is a protein found on the surface of red blood cells. It is named after the rhesus monkey, in which it was first discovered. People who have the Rh factor are Rh-positive, while those who do not have it are Rh-negative.

The Rh factor is important in blood transfusions. If a person receives a blood transfusion from someone with a different Rh factor, their immune system may attack the transfused blood cells. This can lead to a serious condition called hemolytic transfusion reaction.

The Rh factor is also important in pregnancy. If a Rh-negative mother is carrying a Rh-positive baby, her immune system may attack the baby's red blood cells. This can lead to a condition called erythroblastosis fetalis, which can cause serious health problems for the baby.