Factual capsule:
In 1946, Mourant found an antibody in Mrs. Lewis; the antibody reacted with antigens found on erythrocytes as well as in body fluids (saliva, gastric secretion, etc).
The antigens are termed Lewis antigens. The Lewis blood group system is based on this red cell surface antigen.
Most important point to be noted is - These antigens are not produced by the RBC itself. Lewis antigens are components of the exocrine epithelial secretions, and are subsequently adsorbed on the surface of the RBC.
The Lewis gene on chromosome 19 is called secretor gene.
The Lewis antigen is termed secretor antigen and the Lewis blood group is called secretor group.