Which statement is true concerning Group B individuals?

• A. Anti-A in their serum
• B. Anti-B in their serum
• C. They have no antibodies in serum
• D. They lack A antigens on RBCs

Answer: (A)

In ABO typing, the antibodies present in a person’s plasma target the antigens they do not have on their own red cells. Group B individuals have the B antigen on their red cells, so they form antibodies against the A antigen. That means their serum contains anti-A antibodies, which is the statement that best describes their serology.

Because they carry the B antigen, they would not be expected to have anti-B antibodies in their serum. They do have red cells that lack A antigens, which is true, but the most characteristic serum finding is the presence of anti-A. Also, the option claiming no antibodies in serum is incorrect since anti-A is present.