Packed red blood cells red cells with both are called AB. Except in unusual cases like infants or seriously immunocompromised individuals, all people will have antibodies to any ABO blood type that isn't present on their own red blood cells, and will have an immediate hemolytic reaction to a unit that is not compatible with their ABO type. In addition to the A and B antigens, there are rare variations which can further complicate transfusions, such as the Bombay phenotype. The Rh blood group system consists of nearly around 50 different antigens, but the one of the greatest clinical interest is the "D" antigen,
Hh blood group Hh blood group The h/h blood group, also known as Oh or the Bombay blood group, is a rare blood type. This blood phenotype was first discovered in Bombay, now known as Mumbai, in India, by Dr. Y. M. Bhende in 1952. It is mostly found in India, Pakistan, and Iran. The first person found to have the Bombay phenotype had an interesting blood type that reacted to other blood types in a way never seen before. The serum contained antibodies that reacted with all red blood cells' normal ABO phenotypes. The red blood cells appeared to lack all of