Lewis system

This blood group is not synthesized by the RBCs, but the antigens derived from body secretions are adsorbed, or incorporated, into the RBC membrane. The Lewis antigen system is associated with the secretor system and ABO blood group system. Le(a-b+)is the most common Lewis phenotype seen in the white population (75%) and the black population (55%). Le(a+b-) occurs in roughly equal proportions in both populations (23%), while Le (a-b-) is far more common in the black population (22%). Lewis antibodies are rarely of clinical significance.