To test for the Bombay blood group, which antigen should the patient's red blood cells be mixed with?

The correct answer is to mix the patient's red blood cells with Anti-H serum. The Bombay blood group, also known as Oh phenotype, is characterized by a lack of the H antigen on the surface of red blood cells. This absence means that individuals with the Bombay phenotype do not express A or B antigens either, since A and B antigens are derived from modifications of the H antigen.

When testing for the Bombay blood group, the primary focus is on the detection of the H antigen. Therefore, using Anti-H allows for the identification of red blood cells that lack this antigen, thus confirming the Bombay phenotype. In individuals with this phenotype, the reaction with Anti-H will be negative, indicating the absence of the H antigen.

The other antigens mentioned, such as Anti-A, Anti-B, and Anti-Leb, are utilized for testing different blood group systems but are not relevant for identifying the Bombay blood group specifically. Anti-A and Anti-B are used to determine the presence of A or B antigens, while Anti-Leb is used for the Lewis blood group system and has no association with the H antigen detection necessary for confirming the Bombay phenotype.