H-substance

H-substance

or

H-antigen

the carbohydrate precursor of the A and B antigens found in red blood cells (see ABO BLOOD GROUP) and in various tissue fluids (see SECRETOR STATUS), recognized by an anti-H-reagent made from gorse seeds.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005