Individuals with the Bombay phenotype (Oh) will always have naturally occurring which antibody?

Individuals with the Bombay phenotype, also known as Oh phenotype, have a unique genetic makeup that leads to the absence of the H antigen, which is the precursor for A and B antigens found on red blood cells. Because of this lack of H antigen, individuals with the Bombay phenotype will produce antibodies against this antigen, resulting in the presence of naturally occurring anti-H antibodies.

This response occurs because the immune system recognizes the missing H antigen as a foreign substance. Consequently, when these individuals are exposed to blood containing H antigen (which is present in all other ABO phenotypes), their immune system may react against it, potentially causing hemolysis.

The presence of anti-H antibodies is characteristic of the Bombay phenotype and distinguishes them from other blood types, leading to important implications for blood transfusions and compatibility. Understanding this is crucial for managing patients with the Bombay phenotype, as they can only receive blood from other Oh phenotype individuals to avoid adverse reactions.