Type O blood contains what?

• A. AB-agglutinogen present, with A and B antigens
• B. No AB-agglutinogen, with no A or B antigens
• C. No AB-agglutinogen, w/ A antigen only
• D. No AB-agglutinogen, w/ A & B antigens

Answer: (D)

Type O is defined by the absence of A and B antigens on the surface of red blood cells. That means there is no AB agglutinogen present. In the plasma, individuals with type O have antibodies against both A and B antigens (anti-A and anti-B). So the best description is no AB agglutinogen on the cells and the presence of anti-A and anti-B antibodies in the plasma. This combination explains why type O can donate blood to any type (no A or B antigens on donor cells) but can only receive from type O (antibodies would attack A or B antigens if present).