[Amh, a Bombay variant with cryptantigen H]

Untreated red cells of the Bombay variant Amh have traces of A. They are Le(b)-positive but H-negative. Following RDE-(Receptor destroying enzyme) treatment H is demonstrable by anti-HLa, -BHEe, and -HUe but not by anti-HLt. This type of reaction resembles that in O-newborns: H is present only in the form of a glycolipoid but not in the form of a mucoid. The barrier of neuraminic acid prevents recognition of H as his own. Anti-H is present. It has been shown that H as a precursor is necessary only for A1 but not for Am, A3, and A2.