Immunohistochemical localization of Leu-M1 carbohydrate antigen in human oral squamous cell carcinoma.

Twenty-six biopsy specimens of oral squamous cell carcinomas were examined by the avidin biotin peroxidase complex (ABC) method for the presence of an epithelial cell membrane bound lacto-N-fucopentaose III, known also as Leu-M1 or Lex antigen. In normal oral epithelium, Leu-M1 antigen was expressed on keratinizing epithelia in the stratum spinosum. In well-differentiated carcinomas the antigen was found on the cell membrane of nucleate cells in infiltrating epithelial islands. Such pattern in moderately well and in poorly differentiated carcinomas was minimally expressed and was associated with flattened squamous cells or otherwise recorded negative. Leu-M1 antigen immunoreactivity in normal oral epithelia and in carcinomas was comparable to that of blood group H-2 chain that were examined. It was concluded that the intensity of the reaction parallels the magnitude of differentiation of epithelia. Leu-M1 antigen can serve as a marker of differentiation in oral squamous epithelium.