The H antigen is part of the Hh system and is found on all red cells except those of Oh (hh) Bombay phenotype, which is extremely rare. H is the precursor of A and B and so group A and B people have less H than O people.

The reagent will cause agglutination (clumping) of test red cells, that carry the H antigen, after centrifugation. No agglutination generally indicates the absence of the H antigen.

Lorne Anti-H Lectin blood grouping reagent is prepared from an extract of Ulex europaeus seeds, diluted with a sodium chloride solution containing bovine albumin. The reagent is supplied at optimal dilution for use with the tube technique.