Universal blood recipient means AB blood type. This is because the first thing to consider during a blood transfusion is whether the donor’s red blood cells will have an agglutination reaction with the antibodies in the recipient’s serum. If the recipient’s serum contains antibodies, this will result in an agglutination reaction, leading to the destruction of the red blood cells by lysis. In contrast, AB blood type means that the red blood cell membrane contains both A and B antigens, but there are no anti-A antibodies and no anti-B antibodies in the serum. In other words, no transfusion reaction will occur when any blood type is given to an AB person, so in the past, AB people were called universal blood recipients. Although AB is the universal recipient of blood transfusion, the principle of homotypic blood transfusion is still used in clinical transfusion. In other words, only in emergency situations and as a last resort can AB blood be transfused into other people’s blood, and as long as AB blood is available, it is recommended that AB blood be transfused.