The aberrant expression of Lewis a antigen in intestinal metaplastic cellsof gastric mucosa is caused by augmentation of Lewis enzyme expression

Immunohistochemical staining showed an aberrant expression of Le(a) antigen in the intestinal metaplastic glands of the gastric mucosa of secretors, a s reported by others. In this study, we have demonstrated for the first tim e that the Lewis enzyme is well colocalized with Le(a) antigen, indicating that the Lewis enzyme is responsible for Le(a) antigen synthesis in the gas tric mucosa. The staining intensity of the Lewis enzyme was much stronger i n the cells with intestinal metaplasia than the cells without metaplasia, r egardless of the secretor status. The amount of transcript of the Lewis gen e was related to the degree of metaplasia; i.e., the more severe the metapl astic change was, the more abundantly the transcripts of the Lewis gene wer e expressed. This augmentation of the Lewis enzyme in metaplastic tissues w as also confirmed by Western blotting analysis using a specific antibody ag ainst the Lewis enzyme. We conclude that intestinal metaplastic change of g astric mucosa is usually accompanied by a marked augmentation of the Lewis enzyme expression, which results in the enhanced expression of Le(a) antige ns, particularly in secretors.