Low-incidence MNS antigens associated with single amino acid changes and their susceptibility to enzyme treatment.

MNS antigens are carried on glycophorin A (GPA), glycophorin B (GPB), or their variants. Antigens at the N-terminus of GPA are sensitive to cleavage by ficin, papain, and trypsin but are resistant to alpha-chymotrypsin. Antigens at the N-terminus of GPB are sensitive to cleavage by ficin, papain, and alpha-chymotrypsin but are resistant to trypsin treatment. These characteristics have been used to aid in the identification of blood group alloantibodies. Recent molecular analyses have identified changes in amino acids that are associated with several low-incidence antigens in the MNS blood group system. This review relates the molecular studies with the susceptibility or resistance of these antigens to treatment of intact red blood cells by proteolytic enzymes.