<P> Rh derives from rhesus and the terms rhesus blood group system, rhesus factor, rhesus positive and rhesus negative are also used . </P> <P> An individual either has, or does not have, the "Rh factor" on the surface of their red blood cells . This term strictly refers only to the most immunogenic D antigen of the Rh blood group system, or the Rh − blood group system . The status is usually indicated by Rh positive (Rh+ does have the D antigen) or Rh negative (Rh − does not have the D antigen) suffix to the ABO blood type . However, other antigens of this blood group system are also clinically relevant . These antigens are listed separately (see below: Rh nomenclature). In contrast to the ABO blood group, immunization against Rh can generally only occur through blood transfusion or placental exposure during pregnancy in women . </P> <P> The rhesus blood type named after the rhesus monkey was first discovered in 1937 by Karl Landsteiner and Alexander S. Wiener . The significance of the discovery was not immediately apparent and was only realized in 1940, after subsequent findings by Philip Levine and Rufus Stetson . This serum that led to the discovery was produced by immunizing rabbits with red blood cells from a rhesus macaque . The antigen that induced this immunization was designated by them as Rh factor to indicate that rhesus blood had been used for the production of the serum . </P> <P> In 1939, Phillip Levine and Rufus Stetson published in a first case report the clinical consequences of non-recognized Rh factor, hemolytic transfusion reaction and hemolytic disease of the newborn in its most severe form . It was recognized that the serum of the reported woman agglutinated with red blood cells of about 80% of the people although the then known blood groups, in particular ABO were matched . No name was given to this agglutinin when described . In 1940, Karl Landsteiner and Alexander S. Wiener made the connection to their earlier discovery, reporting a serum that also reacted with about 85% of different human red blood cells . </P>

Where does rh negative blood type come from