1 D immunoglobulin (RhoGAM) is administered to Rh-negative, unsensitized patients to prevent isoimmunization.

2 The city has a shortage of Rhesus, or Rh-negative blood - a strand rare in China, with only three of every 1, 000 Han Chinese being Rh-negative.

3 Zhu's organization has set up mobile blood centers across Beijing to help to collect 16 liters of Rh-negative blood that he wants to have on standby for the Olympics.

4 The antibodies also attack the red cells of an Rh-positive fetus carried by an Rh-negative woman if she has had a previous Rh-positive transfusion or pregnancy.

5 But just in case there is not enough by the time of the Olympics, the Red Cross says it has a registry of 400 Rh-negative donors who can be called upon to donate in case of an emergency.

6 Roughly 15 percent of Caucasians, and 10 percent of black Africans are Rh-negative, a large portion of those who will make up a majority of tourists during the Games.