Whether or not someone can safely receive a red blood cell transfusion depends on the antigens on the donor red cells and the antibodies in the recipient's plasma. To answer your question, a person of blood type AB+ won't have antibodies against the A, B, or Rh antigens; he or she would be the "universal acceptor." A related notion is that people with O negative (O-) red cells are universal donors and O- blood is regarded as especially valuable to have on hand in the blood bank.