Which can be found in the saliva of an individual with Lewis phenotype Le (a+b-)?

Which can be found in the saliva of an individual with Lewis phenotype Le (a+b-)?

• A. Leb
• B. ABH Lea
• C. None
• D. Lea

Answer: (D)

Lea is found in saliva because the Lewis system in secretions depends on two fucosyltransferases: FUT3 creates Lea (and Leb) from the type 1 precursor, while FUT2 (the secretor gene) adds an α1-2 fucose to form Leb and ABH structures in secretions. In a person with this phenotype, FUT3 is active to make Lea, but Leb is absent due to nonfunctional FUT2 (nonsecretor) or limited secretor activity. As a result, Lea can be detected in saliva, while Leb cannot, and ABH antigens are typically not secreted in this nonsecretor context. Therefore, Lea is the antigen you’d expect to find.

Lea is found in saliva because the Lewis system in secretions depends on two fucosyltransferases: FUT3 creates Lea (and Leb) from the type 1 precursor, while FUT2 (the secretor gene) adds an α1-2 fucose to form Leb and ABH structures in secretions. In a person with this phenotype, FUT3 is active to make Lea, but Leb is absent due to nonfunctional FUT2 (nonsecretor) or limited secretor activity. As a result, Lea can be detected in saliva, while Leb cannot, and ABH antigens are typically not secreted in this nonsecretor context. Therefore, Lea is the antigen you’d expect to find.