Which blood type has both A and B antigens on red blood cells but no antibodies in plasma?

• A. Type AB blood
• B. Type O blood
• C. Type A blood
• D. Type B blood

Answer: (A)

AB blood is defined by having both A and B antigens on the red blood cells while lacking anti-A and anti-B antibodies in the plasma. In the ABO system, the antibodies in plasma react against the antigens that are not present on your own cells. Since AB individuals do not produce antibodies against A or B, there is no immune reaction against transfused cells carrying either antigen. This combination makes AB the universal recipient for red blood cell transfusions. By contrast, type O has no A or B antigens but contains both anti-A and anti-B antibodies in plasma, and types A or B have only one antigen plus antibodies against the other type, which explains why they’re not universal recipients.