Which antibodies are typically present in serum of a Bombay phenotype?

• A. anti-A
• B. anti-B
• C. anti-H
• D. anti-A, anti-B, anti-H

Answer: (D)

Bombay phenotype lacks the H antigen on red cells. Because H is the precursor for A and B antigens, these individuals also don’t express A or B on their own cells. The striking feature of their serum is anti-H antibodies, produced because the immune system recognizes H as foreign. These anti-H antibodies are clinically significant and will react with virtually any normal red cell that carries H antigen (everything except Bombay cells). Anti-A and anti-B are not the defining antibodies in this context and are not typically present as the hallmark response in Bombay serum.